This is a medium size 50 mm brass padlock, but gimmicked in an ingenious manner, along with several keys.
Any of these keys can be made to open or not open the lock. It does not matter whether the performer or a spectator tries to open the lock, it will open or not open when handled as described.
Inspired by Anneman’s “Seven Keys to Baldpate,” this is a completely mechanical version.
Larger size for larger audiences.