Interrupter pump with built in filter, Transistorized switching device instead of points. Should be used with a separate pressure regulator. This silver top standard pump puts out 4.0-4.5 psi at 18 gallons per hour. Ideal for high output engines using twin choke carburettor, ie. Weber/Dellorto with chokes up to 45mm and all SU single carbs plus most twin SU setups. 1/8" NPTF threads on input and output.