The Birchmeier Gasket Set Pump & Tank Repair Kit (10855901)is a gasket set for pumps and tanks. It's a replacement part for worn out or damaged gaskets of Birchmeier backpack sprayers. It's a repair kit Flox 2.5 gallon and the Iris 4 gallon backpack sprayers. The kit includes 5 O-rings and 4 gaskets that can be used immediately. Gaskets should be replaced annually to extend sprayer life and to reduce or prevent unit downtime.