Aluminum alloy, anodized finish; one end 0.558 in. Dia; flatted two sides; 0.442 in. W across flats; other end 0.562 in. Diameter w/three circular grooves; vertical passage holes through each groove, 0.250 in. Bore dia; flated end, 0.312-24 unf 2b, rh thd in end of bore, 2.596 in. O/a lg