Copper alloy; 2.875 in. Od; two recessed slots on ea side of centerd hole 0.562 in. Diameter hole; seven other holes of various sizes through top of plate; hubbed opposite side w/slots 1.938 in. Od of hub; 1.625 in. Id of hub; 0.500 in. Depth of id; 0.438 in. Hub lg; 0.750 in. O.A h of item