Frame - fabricated of 18-8 type 304 stainless steel with exposed surfaces having a #4 satin-finish. All welded construction; welded-frame, corners are welded and ground smooth. Back Panel - Shock absorbing material is placed between mirror and back panel. Standard Mirror Glass - #1 quality, 1/4" (6mm) plate/float glass guaranteed against silver spoilage for 25 years. Meets and exceeds federal specifications DD-M-00411B & C. S. 27.