This is a follower that can be used to gut a core of an ABUS 72/40 tumbler padlock and probably many other lock cores of the same diameter. A simple AAA battery has a diameter that's approximately good enough to gut those locks but since I didn't have one at hand I preferred to design this simple follower to use it for gutting this locks.

Typically used in lockpicking / locksport when repinning or gutting for demonstration purposes.