Used to connect to your filter for back washing purposes.
Simply screw in the hose adaptor into your multi port valve (40mm BSP) on your sand filter. Attach with a back wash hose using a stainless steel hose clamp. With the pump off, select back wash and turn pump on.
This adaptor can also be used on a Cartridge filter to empty your pool water by screwing the adaptor into the return side of your filter.