This is actually a set of iron lockpicking tools. It's used to open large padlocks, doors with huge keyholes, etc. In order to be able to successfully use this - or any lockpick - you need to have someone skilled in the use of lockpicks teach you haw to work a lock without breaking your tools. To use your large lockpick set, issue the USE order: U 398. It takes 3 Action Pts. Should you happen across a large lock in your exploration and you possess
lockpicking skill, you'll automatically attempt to use your lockpicking at no Action Point cost. You can carry 2.