The Fuji Spray Cup Parts Kit is a 12-piece set of handy wearable parts for reliably sealing your cups, for the use with the Fuji Bottom Feed Spray Guns. The kit includes 3 gaskets, 3 diaphragms, 3 strainers and 3 pressure tubes with check valves. Working together, the diaphragm, gasket, strainer and pressure tube protect against paint backup, while the diaphragm effectively prevents the paint from entering the clear plastic pressure tube. Note: This cup parts kit is for the new Fuji cup design and will not fit older 1 Qt. cup models. If the diaphragm of your cup is a bowl-like part, see Fuji cup parts kit part # 2039. If the diaphragm of your cup is flat circular shape, then this is the right cup parts kit.