New English Made BSA Pre-Unit Singles & Twins Primary Gasket. Stop annoying oil links by installing a new primary cover gasket. This primary cover gasket is compatible with models that feature the swinging arm frame. Replaces BSA part number 42-7507. Fits BSA pre-unit twins (A7, A10, Goldenflash, Super Rocket, etc) from 1954-1963. Also fits BSA singles (B31, B32, B33, etc) from 1954-1957. Please refer to your parts book to ensure the best fitment.Made in EnglandO.E.M Part number is 42-7507