SINGLE CYLINDER AND EARLY TWINS 1/4" BSP STAINLESS STEEL DRAIN PLUG

DRAIN, LEVEL OR BLANKING PLUG.
.600" (15.4MM) ACROSS FLATS (3/8" BSW SPANNER SIZE)
3/8" (9.5MM) UNDER HEAD, THIS IS LIGHTLY DOMED WITH A SLOTTED HEAD.
USED ON NORTON SINGLE CYLINDER AND EARLY TWINS (MID FIFTIES BACKWARDS) PRIMARY CHAINCASES.
ALSO USED ON SINGLE CYLINDER CRANKCASES WITH THE DRAIN PLUG IN FROM THE SIDE.  TWO DIFFERENT PLUGS ARE USED, LATER PLUGS ARE SMALLER AND ENTER FROM UNDERNEATH, THE CHANGE OVER IS CIRCA 1948. (SEE PART NUMBER 13765)
THIS PLUG HAS OTHER USES AND APPLICATIONS.  AN OBVIOUS APPLICATION BEING BLANKING OFF UNUSED PETROL TAP THREADS BUT ALSO MANY EARLY DRAIN FILL OR LEVEL PLUGS ON BRITISH MACHINERY MAY WELL USE THIS THREAD.  
THE THREAD IS PARALLEL, 19 TPI WITH A MAJOR DIAMETER SLIGHTLY OVER 1/2". IF YOU MEASURE THE HOLE YOU WISH TO SCREW THIS INTO IT SHOULD BE APPROX 11.5MM.