CLAMP/Round, open size: 1.968 closed size: 1.89 depth: 1, aluminum, anodized finish. Boeing certified. MS28042-1A

MSP avionics clamps eliminate the need for panel removal when repairing or replacing an instrument such as an altimeter or artificial horizon. These patented chem film and anodized finished clamps are rust proof for up to 25 years; made from lightweight, non-conductive aluminum, they make retrofits simpler and faster as well as making the instrument more secure in the panel.
 

This avionics clamp (Alternate Part# MS28042-1A) has a 1.89-inch round size with a 1-inch depth and constructed of anodized aluminum.