Designed to allow the removal of valve springs and valve stem & oil seals with the cylinder head in place. For universal use on SOHC and DOHC engines. Combustion chamber is pressurised via the supplied spark plug air line adaptor which holds the valve in place during the valve spring compression operation. Includes a 22mm compressed air adaptor. Fast set up time due to the twin rail pivot system. Single handed operation. Airline adaptor has 18mm/14mm (male) threaded end to fit spark plug hole.