It's among the long family of the 'Trick Locks', 'Take-Apart' or 'Hidden Mechanism' puzzles. There's a wide variety of these puzzles with very clever mechanisms to open them.
The solution for the Ring Lock is actually directly related to its own name. Also, a good observer might be able to pick a hint in the picture where you see the lock opened. Sometimes, things aren't exactly what they seem...
The presentation of the puzzle is one of the most interesting found in the Trick Lock's family. It's made to look like an antique lock, with the fading golden metal and the floral motif carvings.
Dimensions 6.5 cm x 4.5 cm x 2cm