Valve is a pocket puzzle that feels like cracking the lock to a safe. You'll have to imagine the nature of the hidden mechanism that allows the inner ring to rotate independently of the silver middle ring and the exterior piece of the assembly. Releasing the valve will separate the puzzle into four pieces. Twisting them all back together again is equally difficult. Valve is designed by Finnish puzzle master Vesa Timonen who has also created a variety of other excellent items available here.