For Flox, Iris, Senior, BCS. This is the gasket that goes between the spray valve (gun) & wand. It is the gasket that seems to wear out the fastest. This item is nylon, which is heavier-duty and longer-lasting then the rubber gasket that comes with the new backpack. The price is for 10 gaskets. If you only need 1 gasket, order the Birchmeier Gasket Set. Keep extras on hand for emergencies.