Tested to fit and work on 20" bikes like the Scott Roxter with 2.6" tyres.
Fits the Protaper JUnit bars.
Enough gear spread to keep kids and adults spinning up the hills and keeping up on the flats.

Fits on a Shimano HG (hyperglide) compatible rear hub.  Does not fit or with Shimano Microspline or SRAM XD freehubs.

Note shifter and derailleur isn't compatible with Shimano Tourney.  They pull a different amount of cable.