PAIR Valve Cover for 150cc and 125cc GY6 4-stroke QMI152/157 QMJ152/157 engines.
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.
Emission Control System: Pulsed Secondary Air Injection System (PAIR)
GY6 QMI/QMJ 152/157, Various unlisted makes/models