At 8x magnification, the inner diameter of the ring is 133 mm. The rebuttal is built into the 2nd image plane, so by a magnification change (from 7x to 9x) the distance between the ring of the rebuttand and the target is changed at will. It can only be used the magnification from 7x to 9x. (See Fig. 4 / Reclusor)
Fits all sports rifles (Anschütz, Walther, Feinwerkbau, Bleiker…)