This is a magneto flywheel rotor housing with center nut in excellent used condition, see photos. It fits 1968-72 AJS Stormer 250 370 & 410 singles and Villiers Starmaker Cotton road racers. It says Villiers England right on the outside so you know it's original. It's also no longer available from AJS in the UK. The magnet will hold the clutch diaphragm spring I just listed for sale at the edge, so if you buy them both, they'll ship well together in the same package, even though they are totally unrelated to each other. AJS Stormer part number for the flywheel is 30675. This is another excellent quality used part from your US source for AJS Stormer spares.