Stage6 HPC Zuma , HPC (High Primary Compression) crankshaft for 10mm, or 12mm HQ full-circle crankshaft for higher primary compression in the crankcase. It is entirely made of hardened steel, with reinforced connecting rod. Stage6 opted for a full-circle design instead of the standard design; this way the crankshaft has greater rotational inertia at high rpm. Excellent balancing (45%) reduces vibrations that stress materials and may lead to engine failure. Details: excellent balancing full-circle reinforced connecting rod ONLY AVAILABLE IN HORIZONTAL