This metal & enamel keychain features an unusual pose. It's laying Sonic tapping his fingers on the ground. He'd take up this pose in Sonic CD if left idle for long enough. There is a Japan stock art of the pose, but it's not used frequently. The keychain is cut into the shape of the pose, with goldtone metal. Notice that the lead/chain part is missing here. 

This metal & enamel keychain uses Sonic CD's "impatient laying Sonic" for its design. There is a Japan stock art of the pose, but it's not used frequently. In CD, he would go from foot tapping, to laying down & finger-tapping (shown here) if you left the controller alone long enough. The Key Ring is gold-tone metal, & it uses all 5 colors of enamel. It's a pretty good likeness, though where exactly his other foot is...is not shown. This is an uncommon pose seen on an uncommon keychain, released around the time of Sonic CD (naturally).