This is a flow sensor replacement gasket used in the new style Bestway, Coleman and Lay-Z-Spa brands of inflatable hot tub pumps. If you find that your pump/heater unit is leaking water around your water flow sensor, the seal inside of the cap may be damaged. This is a replacement seal to replace your worn one under the cap. If you are replacing the flow sensor gasket, check your flow sensor cap and the flow sensor magnetic paddle for damage. If you need a replacement magnetic paddle also, you may want to look at my kit that contains the gasket, the nylon retaining pin and the o-ring seal by clicking here.