Universal Parts 57mm Emissions Type Cylinder Head for 150cc GY6B 4-stroke ZNEN engines commonly found in Lance Phoenix, Flyscooters Cadenza, ZNEN ZN150T-18, Xingyue ITA-150, Motorino Cassini, CMS Prodigy, BMS Pathfinder and many more.Emissions Type a.k.a. PAIR is an acronym for Pulsed Secondary Air Injection System. It is an emissions control system used to lower HC and CO emissions. It works by allowing air into the exhaust flow.