Dominator quick-change engine sprocket assembly

Is anyone familiar with this set up?
The gears (21-22-23) are stamped "Talon" and are contained by two circlips on both sides.

They must be for a modern bike where the sprocket is already exposed, so these facilitate quick track side changer.

On a Norton, there’s already so much work required to get to the sprocket, I can’t see any real value in these, it’s only one more nut (albeit a big un) !

It’s made for a race Domi without a chaincase.
I think it would save a little time over breaking the tapper fit each time you want to change a gear.

Not sure it will fit a streetbike with a chaincase and cast stator cage.

Kevin at Nortonraceparts.com seems to have a bunch of Talon products on his website, under "speedway and grasstrack" about 2/3 the way down. Doesn't have those specifically, but I bet he could find out if he doesn't know already.