Replacement Zip Line Pulley for D&D Flyer Zip Line ($12 each). Pulley is made of Glass Reinforced Nylon with integral stainless steel ball bearings (dual stainless steel ball bearings).  Dimensions: Outside Diameter = 2"; Inside Diameter = 13/32" (clearance hole for a 3/8" bolt); Thickness = 1"; pulley fits cable diameter 7/32" and smaller.