Pully wheels. guide wheel: 12T(stainless steel/ceramic bearing). tension wheel: 18T(stainless steel/ceramic bearing). Compatible with EDS TX series. low resistance. Super durable. Carbon cage 118g of total weight WHEELTOP TX pulley wheel cage upgrade kit – the ultimate upgrade for TX series owners who demand aesthetics,smooth shifting, lower resistance, and long-lasting performance. Designed with precision ceramic bearings and ultra light materials, this pulley cage is built to maximize the riding experience for serious cyclists.