When thinking quality belly buster primary clutch weights, think EPI. EPI has 30 + years of real-world manufacturing and engineering of belly buster primary clutch weights. EPI takes a unique approach of testing their belly buster primary clutch weights in a real-world riding environment to ensure their belly buster primary clutch weights meets the requirements of our customers. These quality EPI Belly Buster clutch weights are made from billet tool steel, heat treated and plated for extended life and durability. These clutch weights provide stronger low and mid range power and proportioned to provide a more aggressive upshift.