These are the Inner dirt guards (1 pair) that fit over the front wheel hub.
These fit Harley J F JD FD JDH Models from 1921 to 1928.
The I.D. where these fit over the hub is about 1.97"
They should be tapped on to the hub for a snug fit. Make sure you get them all the way on the hub so they don't interfere with the outer dust guard. You'll have to use a driving tool or piece of pipe to do this.