Sapphire crystal lens with Anti-Reflective coating on one side. 22mm x 1mm.
Insert the lens with plastic still on facing the outside. Be careful not to touch the exposed AR coated side. The AR coated side faces inward. Do not touch or wipe AR coated suface as it will mar the finish. Once in place peel away the plastic.
McGizmo says "The window has a vinyl piece on the non AR side. The AR coating is very delicate. Blow it off to remove any dust but that is it! Install the window with the vinyl side out."