Valves, inlet, Norton twins Atlas P11 G15 (ea). UK made, best quality inlet valve: Overall Length: 3.939" (100MM); Stem Diameter: 5/16"; Head Diameter: 1 1/2" (38MM); Weight: 57g. Concave head and undercut stem diameter in the port improves flow and combustion. Pulse plasma nitride coating and super polishing reduces friction and wear allowing a slight increase in stem diameter in the guide which helps to reduce emissions and reduce oil consumption whilst improving combustion. En52, hardened tip. Original part number 24330 - valve inlet (all 750)