Best M4 Lock Washers in 2026

Daisy
Last Updated: Jul 17, 2026

At a Glance: Our Top Picks for M4 Lock Washers

NEIKO 50400A Stainless Steel Lock and Flat Washer Assortment | 350 Piece Set | 12 Different Sizes in Spring Lock and Flat Design | Prevent Loose Fasteners
#TOP1
Neiko 50400A Stainless Steel Lock And Flat Washer
9.8
PM SCORE
The Hillman Group 830678 Stainless Steel 5/8-Inch Split Lock Washer, 25-Pack
#TOP2
The Hillman Group 830678 Stainless Steel 5/8-Inch Split
9.7
PM SCORE
Hilitchi 400-Pcs [8-Size] 304 Stainless Steel External Internal Tooth Star Lock Washers Assortment Kit - Included: M2 M3 M4 M5 M6 M8 M10 M12
#TOP3
Hilitchi 400-Pcs [8-Size] 304 Stainless Steel External Internal
9.6
PM SCORE

* PickSmartly editors independently research, review, and endorse the top products through comprehensive data analysis. We may earn a commission for qualifying purchases made through our product links.

Summary of the Best M4 Lock Washers of 2026

Market Overview
M4 Lock Washers Reviewed
  • Reviews Analyzed: 4620 Items
  • PM Avg. Rating: 6.4 / 10
14 Products Evaluated
  • Highest Price: $17.99
  • Lowest Price: $6.96
  • Avg. Price: $12.04

Neiko 50400A Stainless Steel Lock And Flat Washer Assortment | 350 Piece Set | 12 Different Sizes In Spring Lock And Flat Design | Prevent Loose Fasteners

NEIKO
50400A
8.10 X 4.15 X 1.15 Inches
SELLER SELLER SCORE AMAZON FULFILLED PRIME FREE SHIPPING
Amazon.com 9.68

Features

GALVANIZED STAINLESS STEEL: These lock and flat washers provide excellent protection and security for nuts and bolts. They are made with galvanized stainless steel for long-term use and outstanding durability.

VERSATILE & COMPATIBLE: These assorted washers come in multiple sizes to fit all your screws, nuts, and bolts. Each washer features a solid bearing surface to prevent the nut or bolt head from tearing through the material.

OPTIMAL SURFACE AREA: Each stainless-steel flat or lock washer easily deflects the screw or bolt load, spreading the weight evenly for a secure and sure fit. These washers for screws and bolts are ideal for use at home or in the workshop.

THE RIGHT SIZE: This set of washers contains a wide variety of sizes. It includes lock washers in sizes #6, #8, #10, 1/4", 5/16", and 3/8" and flat washers in sizes #6, #8, #10, 1/4", 5/16", and 3/8".

CONVENIENT STORAGE: Keep your washers ready for your next home or automotive project. This 350-piece set comes in a convenient, sturdy plastic box with divided compartments for easy storage and an inside lid display for easy organization.

The Hillman Group 830678 Stainless Steel 5/8-Inch Split Lock Washer, 25-Pack

THE HILLMAN GROUP
830678
2.70 X 2.40 X 1.50 Inches
0.60 Pounds
SELLER SELLER SCORE AMAZON FULFILLED PRIME FREE SHIPPING
Amazon.com 9.68

Features

Commonly used in applications using a bolt or a screw where two pieces are being joined together

Split ends grip the material surface to prevent loosening during vibration

18-8 Stainless Steel finish for good corrosion resistance

Use with like nuts and bolts of similar diameter

For use with any indoor or outdoor project with treated lumber

Hilitchi 400-Pcs [8-Size] 304 Stainless Steel External Internal Tooth Star Lock Washers Assortment Kit - Included: M2 M3 M4 M5 M6 M8 M10 M12

HILITCHI
HDPHX-400
SELLER SELLER SCORE AMAZON FULFILLED PRIME FREE SHIPPING
Hilitchi 9.88

Features

【✔】High Quality Stainless Steel External Internal Tooth Star Lock Washers Assortment Set

【✔】Set Includes 8 Most Used Sizes: M2(2.5) M3 M4 M5 M6 M8 M10 M12 【Metric, please See Picture 2 for Specific Dimensional Size】

【✔】Made of 304 Stainless Steel Material, Very Good Corrosion Resistance, It Can Be Used in a Humid Environment

【✔】Package Quantity: 400-Piece, All of Washers Will Be Packed in A Sturdy Transparent Plastic Case, Can Be Use for A Storage Box

【✔】 A Lock washer exerts a spring force between the fasteners head and the substrate, which maintains the washer hard against the substrate and the bolt thread hard against the nut or substrate thread, creating more friction and resistance to rotation.

Hilitchi 300-Pcs 304 Stainless Steel External Tooth Star Lock Washers Assortment Kit - Included: M2.5 M3 M4 M5 M6 M8 M10 M12

HILITCHI
HETW-300
SELLER SELLER SCORE AMAZON FULFILLED PRIME FREE SHIPPING
Hilitchi 9.88

Features

♛ High Quality Stainless Steel External Tooth Star Lock Washers Set

♛ Set Includes 8 Most Used Sizes: M2.5 M3 M4 M5 M6 M8 M10 M12

♛ Made of 304 Stainless Steel Material, Very Good Corrosion Resistance, It Can Be Used in a Humid Environment.

♛ Package Quantity: 300-Piece, All of Washers Will Be Packed in A Sturdy Transparent Plastic Case, Can Be Use for A Storage Box

♛ Perfect for electrical connections on household and commercial appliances, automotive and marine uses in which the power source has a threaded/bolt-type connection

Qteatak 260 Pcs 7-Size 304 Stainless Steel Flat Washer & Lock Washer Assortment Set (Size Included: M2.5 M3 M4 M5 M6 M8 M10)

QTEATAK
JF0003
SELLER SELLER SCORE AMAZON FULFILLED PRIME FREE SHIPPING
JianFeng Store 9.86

Features

1. 304 Stainless Steel Spring Lock Washers Set,Good Corrosion Resistance, It Can Be Used in a Humid Environment.

2. 7 Most Used Sizes: M2.5 M3 M4 M5 M6 M8 M10, Flat & Lock

3. 260 Pieces,Packed in A Sturdy Transparent Plastic Case

4. As a Reliable, Responsible Professional Producer, We Will Not Cut Corners on the Quality of Products.

5. NOTE Cause of the Small Size, Please Keep it Properly, Avoid to Play by Children and Lead to Accidental Swallow or other Dangers!

5/16" Stainless Lock Washers (100Pack), By Persberg, 304 18-8 Stainless Steel (120-5)

PERSBERG
A3040001005L16W
SELLER SELLER SCORE AMAZON FULFILLED PRIME FREE SHIPPING

Features

HIGH QUALITY STAINLESS: These 100 Piece Lock Washers are 100% 18-8 (304) Stainless Steel which is one of the highest forms of corrosion resistant steel, making it last longer than other hardware on the market today.

WASHERS THAT YOU CAN DEPEND ON: Our hardware is very strong and is great for both indoor and outdoor use. The stainless steel is superior to regular steel and provides excellent rust resistance in water applications.

GREAT TO KEEP AROUND: Persberg hardware is great to have around for use in wood and wet environments. Persberg washers are the highest quality available on the market and we stand by our claim 100%. They are strong, corrosion resistant and will support all of your projects.

DIMENSIONS: Inside Diameter: i.d.: 5/16"-21/64" o.d.: 25/64"-29/64" | Quantity: 100 pcs | Material: 18-8 (304) Stainless Steel

LIFETIME GUARANTEE: Try our product Kit with NO risk and 100% money-back guarantee – NO questions asked!

Small Parts Internal Tooth Lock Washer, Steel, Zinc Finish, 1/4" Bolt Size, 0.2620" Id, 0.4690" Od, 0.0260" Thick, Pack Of 100

SMALL PARTS
B000NSDS4E
0.07 Pounds
SELLER SELLER SCORE AMAZON FULFILLED PRIME FREE SHIPPING
Amazon.com 9.68

Features

Lock Washers ensure a tight assembly

Plain Steel fasteners are suitable where strength and value are the primary considerations

Size Name corresponds to matching screw or bolt size

Country of origin: China

Pzrt 50Pcs 1/4 Inch 304 Stainless Steel Spring Washer Split Lock Washers, Silver

PZRT
LOCKWASHER-14-50
SELLER SELLER SCORE AMAZON FULFILLED PRIME FREE SHIPPING
PZRT 9.85

Features

304 stainless steel Inner diameter 1/4 inch split lock washer.

For use with 1/4 inch bolts and machine screws.

Great corrosion resistance for outside applications.

Tensile - 100,000 psi to 125,000 psi, Hardness - 85 Rockwell B.

Quantity: 50pcs

#10-32 Keps Nuts With External Tooth Washer, K-Lock Keps Nuts 304 Stainless Steel Kep Lock Nut, 100Pcs-Pack

INSTOCKBOLTS
KN#10-32
SELLER SELLER SCORE AMAZON FULFILLED PRIME FREE SHIPPING
Instockbolt 9.96

Features

🔧【DIMENSION】#10-32

🔧【MATERIAL】Keps Nut made of 304(18-8) stainless steel, good thermal conductivity and heat resistance, firm and corrosion resistant, can ensure long time using.

🔧【EASY TO USE】K-Lock Nuts feature a built in external tooth lock washer that is free spinning, The teeth on the lock washer can bite into the surface and help lock the nut into place.

🔧【PACKAGE CONTENT】100pcs x Keps Nut

🔧【REST ASSURED】24h private customer service to respond to after-sales problems.

900 Pieces 304 Stainless Steel Spring Lock Washers For Screws Bolts, Helifouner Lock Washers Assorted Kit, Stainless Steel Lock Washers, Lock Metal Washers (M2 M2.5 M3 M4 M5 M6 M8 M10 M12)

HELIFOUNER
HELIFOUNER---LOCK---WASHER
SELLER SELLER SCORE AMAZON FULFILLED PRIME FREE SHIPPING
HELIFOUNER 9.89

Features

【Sizes】M2 M2.5 M3 M4 M5 M6 M8 M10 M12, total 900 pieces/9 sizes of the most commonly used stainless steel spring lock washers, metal lock washers in a plastic case, different sizes can satisfy your different needs.

【Design】Lock washers, spring lock washers, metal lock washers are designed for electrical connections on household and commercial appliances, automotive and marine uses in which the power source has a threaded/bolt-type connection.

【Material】304 Stainless Steel, stainless steel material which have good corrosion resistance in bad environment like high temperature, cold weather, and high humidity areas. They have superior rust resistance and excellent oxidation resistance, which can ensure long time using.

【Weak Magnetic】The magnetic properties of 304 stainless steel due to the structure transformation reasons are not at the same level as the magnetic properties of stainless steel of other materials, which means that the magnetic properties of 304 steel always show weak magnetic properties.

【Wide Applications】Highly compatible with screws, nuts and bolts of same sizes and feature solid bearing surface to prevent nut/bolt head from tearing through material. Designed to spread the load of a screwed fastening and prevent loosening in industrial, shop, decks and fence building, automotive and home appliances.

Spring Lock Washers Split Lock Zinc Washers Assortment Kit M3 M4 M5 M6 M8 M10 800 Pieces

BUSY-CORNER
SPLIT LOCK WASHERS - 800 PIECES
SELLER SELLER SCORE AMAZON FULFILLED PRIME FREE SHIPPING
BUSY-CORNER 9.91

Features

【WIDE APPLICATION】Split lock zinc washers prefect use for around the house and yard decorations, electrical connections on household and commercial appliances, automotive and marine uses in which the power source has a threaded/bolt-type connection.

【DETAILED SIZE】Spring lock washers set includes 6 most used sizes, M3=250PCS, M4=250PCS, M5=150PCS, M6=100PCS, M8=25PCS, M10=25PCS.

【HIGH QUALITY】Split lock washer made from zinc.

【HANDY PACKING】800pcs washers in a clear plastic case, makes it easy to find correct size quickly, saves your time of running around looking for a particular size washer.

【CUSTOMER SERVICE】You are unsatisfied for any reason, return your goods with no questions asked and BUSY-CORNER STORE will provide a full refund.

(400 Pcs) #10X1/2" Sealing Washers 304 Stainless Steel Neoprene Epdm Bonded

WENSILON
00002
0.55 X 0.55 X 0.13 Inches
SELLER SELLER SCORE AMAZON FULFILLED PRIME FREE SHIPPING
WenSiLong 9.75

Features

Material: Our Sealing Gasket Is Made Of 304 Stainless Steel And Epdm Rubber, Durable And Long Life With Good Rust Resistance, You Do Not Have To Feel Frustrated By Rust

Package Quantity: Our Products Are Strictly Controlled By The Quantity Of Each Package, And Packed In A Strong And Durable Box, You Do Not Have To Worry About Receiving A Broken Package And The Number Of Packages Does Not Match The Actual

Features: The Sealing Washer Is Rubber On One Side And Metal On The Other Side Of The Washer. Suitable For Use In Metal Plates, The Rubber Helps To Solve The Problem Of Vibration Noise, The Gasket Helps To Improve The Friction Of The Screw To Enhance The Sturdiness, They Are Good Helpers For Your Work.

Wide Range Of Applications: Suitable For Use In Self-Drilling Screws, Widely Used In Electrical Equipment, Industrial Machinery, Construction, Etc.

Contact Us: If You Have Any Questions About Our Products, Please Feel Free To Contact Us At Yibian

Wensilon (600Pcs)1/4" Stainless Steel 304 Metal Stainless Lock Washers For Screws And Bolts, Suitable For Factory Maintenance, Kitchen, Store And Outdoor Construction

WENSILON
DHDQ002
SELLER SELLER SCORE AMAZON FULFILLED PRIME FREE SHIPPING
WenSiLong 9.75

Features

WHAT YOU GET: 100 stainless steel #8x3/8" Spring Lock Washers ideal for use in sheet metal and wet environments with very high form corrosion resistance in 304 material

304 MATERIAL: Our Spring Lock Washers are made of 304 stainless steel, which is longer lasting than other hardware on the market and will last longer in harsh environments such as high temperature, low temperature and high humidity.

WIDELY USED: Our Spring Lock Washers can be used to fix bolts with diameter smaller than the hole of the washer, suitable for general industry such as indoor decoration, outdoor construction, electrical repair and furniture repair.

PRODUCT FUNCTION: Our Spring Lock Washers are used to distribute the load of threaded bolts, screws and nuts, providing a smooth load bearing surface

SIZE: Inner diameter 0.475in Outer diameter 0.295in Thickness 0.07in

Wensilon (120Pcs)1/4"X1 Stainless Steel 304 Metal Flat Washers For Screws And Bolts, Suitable For Factory Maintenance, Kitchen, Store And Outdoor Construction

WENSILON
PD0010
SELLER SELLER SCORE AMAZON FULFILLED PRIME FREE SHIPPING
WenSiLong 9.75

Features

WHAT YOU GET: 100 stainless steel 1/4"x1 flat pads ideal for use in sheet metal and wet environments with very high form corrosion resistance in 304 material

304 MATERIAL: Our pads are made of 304 stainless steel, which is longer lasting than other hardware on the market and will last longer in harsh environments such as high temperature, low temperature and high humidity.

WIDELY USED: Our flat pad can be used to fix bolts with diameter smaller than the hole of the washer, suitable for general industry such as indoor decoration, outdoor construction, electrical repair and furniture repair.

PRODUCT FUNCTION: Our flat washers are used to distribute the load of threaded bolts, screws and nuts, providing a smooth load bearing surface

SIZE: Inner diameter 0.27in Outer diameter 1in Thickness 0.06in

Top 10 lock washers Brands on Amazon

Here is the list of top-rated brands that were evaluated by PM.

Brand Count
Wensilon 3
Hilitchi 2
Busy-Corner 1
Helifouner 1
Instockbolts 1
Neiko 1
Persberg 1
Pzrt 1
Qteatak 1
Small Parts 1

Top 10 lock washers Brands Pie Chart


We've carried out a comprehensive analysis of 4,620 reviews on lock washers, using our selection criteria to identify the best options in the fasteners. Our findings reveal that most customers typically select lock washers priced around $12.04, with top brands including wensilon, hilitchi, helifouner, qteatak, busy-corner, persberg and pzrt and the hillman group

Our team of expert editors reviewed these high-quality items and handpicked the top 14 lock washers for your consideration. We've also done extensive research on numerous sellers, identifying the best ones in the fasteners category. These include wensilong, hilitchi, helifouner, jianfeng store, busy-corner and pzrt and amazon.com .

We are dedicated to assisting our users in finding the right washers Products based on their needs, saving them considerable time when choosing which lock washers to buy. We take pride in the number of satisfied users we've helped through our thorough and insightful reviews.