All grab bars are fabricated of satin finish 18 gauge type 304 stainless steel tubing. In compliance with strength requirements of ADA Guidelines. Cover snaps over mounting flange dimples to conceal screws. Concealed mounting flange is 3 1/8" OD diameter with two screw holes and three locking dimples and is 1/8" thick, type 304 stainless steel. Cover is type 304 stainless steel with satin finish, 22 gauge, 3 3/16" diameter. 1 1/2" O.D.