Set of two rings; polytetrafluoroethylene ring, split; outer and recessed ring; outer ring w/two grooves 2.500 in. Od, 1.800 in. Id, 0.330 in. H, 0.400 in. W; groove size 0.300 in. W, 0.075 in. Deep; recessed ring size 2.300 in. Od, 1.900 in. Id w/four grooves 0.300 in. W, 0.075 in. Deep; aluminum bronze