Thomas Service Kit. Kit includes 2 ea: Pump Heads w/Valves, Diaphragms, Diaphragm Rings, Diaphragm nuts, Diaphragm washers. Kit is compatible with standard Thomas YP-30DU, YP-40DU, YP-50DU, YP-30VC, YP-40VC, YP-50VC models (This item currently has a tariff surcharge which will be added to your order as a separate line item. Tariff surcharges are subject to change.)