This 1-1/2" threaded hose connector adapter is an all purpose part designed to thread onto pool filters & pumps. 

This combo hose adapter is 1-1/2 inch MPT and 1-1/4 inch hose. 

Used to connect a pool filter hose to a filter or pump, or to connect your backwash hose to the filter valve. Use a stainless steel hose clamp to hold hose firm.