18-gauge, type 304 satin stainless steel exterior finish with molded grey color polyethylene interior. Unit 37" W x 23" H (940 x 585mm). Depth (closed) 3⁄4" (20mm). Extension (open) 15 1⁄4" (385mm). Rough Wall Opening: 35 1⁄2" W x 20 1⁄2" H (900 x 520mm), 4" (100mm) min. depth.