Its 3/5ths of the 5 speed N 1:1, .75, & .6 ..

You can screw on a freewheel, they threaded the spline tips..

I have an AW3, freewheel down hills is better on my Knees
over the many decades of riding



White Dos Freewheel will offer a split ratio, 2nd cog in space of 1,

but you are back to derailleurs to shove the chain back and forth..