Engineered To Provide More Uniform Load Distribution, Split Lock Washers Are Great For Any Indoor/Outdoor Project. Ideal For Situations Where Potential Loosening From Corrosion Or Vibration Is A Concern, Split Lock Washers Are Used To Prevent Nuts And Bolts From Coming Loose. These Fasteners Contain Split Ends That Help "Lock" Into The Mating Material, Thus Providing A Locking Feature When Tightened Beneath A Nut. The Zinc Finish Provides Moderate Corrosion Resistance. Use With Treated Lumber In Applications With Like Nuts And Bolts Of Similar Diameter. *