The added screw driver slot makes it much easier to turn the armature when setting the timing before tightening the sprocket. Available only from JSmotorsport
Reusable fiberglass reinforced silicone gasket below needs no sealer and makes it easy to adjust chain tension because you can always reposition it. The plugs seal up the countersunk screws. Only mags from JSM come with sealer between the adapter plate and mag body for an oil tight seal.