The AIRPAX / SENSATA 279-2-1REC4-53F-9-9-85 is a hydraulic magnetic circuit protector within the 209 series. It offers a combination of power switching and accurate, reliable circuit protection in a compact, single or multi-pole unit, making it suitable for branch circuit applications like EDP, air conditioners, panel boards, and lighting controls. Utilizing the hydraulic-magnetic principle, it adapts to various environments and minimizes nuisance tripping due to temperature variations. It is designed to withstand high pulses without affecting normal delay curves.