The Fuji industrial spray equipment cup parts kit is a 9-piece set of handy wearable parts for reliably sealing your cups. The kit includes 3 gaskets, 3 diaphragms, and 3 pressure tubes with check valves. Older cups with the black-colored lid can be converted to use the durable plastic diaphragm. Working together, the diaphragm, gasket, and pressure tube protect against paint backup, while the diaphragm effectively prevents the paint from entering the clear plastic pressure tube.