“DSR” Hubs – for assembly with “AR” plate sprockets to make double-single of substance sprockets. Finish bore hubs have got standard keyway and 2 setscrews.
Ready Sprockets are a variety of sprockets and hubs drilled and tapped for basic, convenient assembly with standard hex head cap screws. For No. 35 through No. 100 Chain, with share finished bore hubs to support shaft sizes through 2-3/4″ READY SPROCKET HUB TYPE DSR diameter, plus a variety of square, hex, 
spline, and tapered key bores.