Ring (open) silver Ø 8mm × 1.5 mm (per 10)

This ring is not welded or closed therefore you can hook other objects to it and bend it closed.

inside of the ring is measured

We measure the inside of the buckles, O-ring etc. (= the size of the leather belt that can go through it)
The size of O-rings is the inside diameter, and with the D-rings we measure the inside of the straight side.