Washer for drain plug, Norton post 1948

Washer for sump drain plug for Nortons singles and twins 1948 on. Models 7, 1 ,16H, ES2, 18; chaincase drain plug later featherbed twins; oil tank drain plug twins 1955+
Original part number:
13881- drain plug washer (washer changed in 1957 but this one will still fit) x 1
13833 - drain plug washer x 0