Petrol (fuel / gas) adaptor male to female threaded, 3/8 BSP (old fashioned parallel BSP thread not tapered) to 1/4 BSP, brass, plain eg no sealing washer. Has large enough hole in centre to fit fuel filter built into tap. Allows a tap to be stepped away from the tank to allow clearance for bolts and other obstructions. Ideal for converting large holes on BSA, Ariel ,early Triumph etc to standard 1/4 BSP tap. Neat looking, old style not the new chunky ugly ones.