Master Lock - Keyed Alike Brass Locks #4NKABLF-4 BUMP 4 Pack BumpStop Advanced Cylinder Technology. Keyed Alike 1-9/16" (40mm) wide laminated brass body, 9/32" thick solid brass shackle, and brass cylinder. Brass construction offers maximun corrosion resistance. 4 pin cylinder helps prevent picking. Thousands of key changes maximize key integrity. Ideal for marine and other harsh environments.