Front sight irises will fit Sinclair, RPA, Anschutz, Diana, Steyr, and other front sights. All front sight irises have calibrations laser cut and have a black matte non-reflective finish internally and externally. Available in 18mm or 22mm. Glass element (not plastic) with an adjustable ring. The glass has been specially finished on optical equipment to eliminate any distoration of the image. Adjustment range: 2.4mm - 4.4mm.
Sinclair, Issue:3B, Page:213