Shackle is concealed to make it difficult to cut. Choose these locks if you want individual locks or groups of locks that open with their own key, but also open with a master key. The included keys have random key numbers; master keys are sold separately. Stainless steel-body locks are more corrosion resistant than steel-body locks, but are not as strong.

Stainless steel shackles are more corrosion resistant than hardened steel shackles, but are not as strong.

Pin-tumbler key locking mechanisms are the most difficult locking mechanisms to pick. When choosing between padlocks with four or five pins, the lock with five pins is harder to pick.