Featuring the DuraBall mirror mounting and positioning system which includes a non-corrosive nylon ball joint for smooth, long lasting operation (mirror must be loosened prior to repositioning). Both mirrors features an outer gasket for edge shock protection and a mirror back and ball joint system that is covered by a five year guarantee against cracking or breaking. 5/16"-18 mounting stud and hex nut included. Priced each. Replaceable 1/8" silvered glass with 21" radius of curvature.