A special design for a metal trick lock.The Houdini Under Lock has internal mechanism that needs to be figured out, so a simple use of the provided key will not do it! Puzzle Locks or Trick Locks cannot be opened like normal padlocks. A solution, or trick, needs to be found to crack the lock! Pit your wits against this puzzle in order to crack the lock. Puzzle locks have been made for many centuries and have foiled burglary attempts, kept secrets hidden away and helped escapologists baffle audiences. Over the years they have been some of the best and most popular puzzles ever invented.