40mm (1-1/2") Trap Inlet Square Section Washer

This square profile 1-1/2 inch trap inlet washer makes the seal between the trap and waste fitting on your bath or sink.

It's called a 1-1/2 inch washer, because it suits a waste trap with a 1-1/2 inch BSP thread, not because the washer itself measures 1-1/2 inch.