McGard wheel locks for boat trailers are machined from high quality steel through-hardened and then triple-nickel chrome plated. For boat trailers with steel or alloy wheels simply replace one of the lug nuts with a McGard wheel lock that's it. McGard wheel locks are 1/2-20 cone seat. Note most OEM trailer wheels use 1/2-20 cone seat lug nuts. Available for both Single and Double axle.