The Ives Wall Bumper Stop WS407-CCV our economically price concave wall bumper. The metal ring is a wrought stainless steel, otherwise known as stamping. It features a concealed tamper-proof mounting, and is shipped pre-assembled to the back plate is reduce installation time. Installation is easy, just insert the screw driver through the pin hole in the rubber and tighten. The bumper is 2-1/2" in diameter and projects out 1".