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