Ring has 3 types can be selected: "No.1 Ring" is a O-shape ring, "No.2 Ring" is a special-shaped ring, "No.3 Ring" works with a screw.
Ring has 4 sizes (inner diameter) can be selected: 40 mm, 45 mm, 50 mm, 55 mm.
Cage of No.1/2 ring length is about 53 mm, inner diameter is about 32 mm.
Cage of No.3 ring length is about 50 mm, inner diameter is about 33 mm.
These sizes may have a little error because it's made by hand.
Weight is about 180 grams.