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