REAR SPROCKET CHROMOLY 47T-420 BLACK K/G/HThe Dirt Tricks Rear Sprocket was designed and patented by Dirt Tricks president and engineer Greg Burns in 2002, using his knowledge of aerospace steels, heat treatments, as well as FEA stress analysis His goal was to create a sprocket that would last an entire season of hard riding, yet be comparable in weight to aluminum, the end result has proven to be the toughest, most durable off road sprocket available Our Diamond Black and Chromatic Rear