The padlock design looks similar in size and weight to a locked one might find at the gym, but look out - there's no key or combination of numbers to solve this one! Just pick it up and you'll quickly gain an appreciation for the challenge that lies ahead - this puzzle will not open easily! The interior is comprised of two elliptical pieces, locked together tightly around the circular pieces and obstinately refusing to be released. But don't give up! This seemingly simple design may take hours to unravel - but your mission is only complete when you have put the lock back together again. The theme is "obstinacy." Designed by Korean designer JinHoo Ahn. Level 5 (out of 6) puzzles are considered difficult.