Featuring a stainless steel finish and an outer gasket for edge shock protection. 5/16"-18 mounting port. 92-9122 features a 1/8" silvered replaceable glass with 21" radius of curvature. 92-9126 has over 32 square inches of viewing area and replaceable 1/8" FSC glass. Priced each. Over 55 square inches of viewing area and replaceable 1/8" FSC glass.