Featuring surface flatness of 4–6 λ, TECHSPEC® First Surface Mirrors have protected silver coated surface that is designed to face incident light, minimizing energy loss by preventing light from passing through glass substrate. Metal coating includes protective dielectric overcoat layer that prevents damage from atmosphere or from cleaning. Offered in circular, square, and rectangular dimensions, mirrors provide average reflectance of >98% at 500–800 nm and >98% at 2,000–10,000 nm.