Coleman 6391091 Pump Cup and Push Nut for Liquid Fuel Lanterns. Package includes: 1 pump cup and 1 push nut. Pump Cup Material: Neoprene Rubber; Push Nut Material: Metal. The pump cup acts as a seal inside the pump in order to prevent air leakage and retain pressure. The pump clip (also called a pump nut) sits on the end of the plunger shaft, next to the pump cup on the side closer to the inside of the lantern; it prevents the pump cup from sliding off the shaft. Note that the pump cup will need to be coated in Pump Lube before use, found as part # 200K2251. Made in the USA. Genuine Coleman part.