Series RSS-495-11 Air Sensing Switch Kit contains compact, economical switches designed for a residential furnace and light commercial aftermarket applications. The RSS-495 switches have an adjustable set point range of 0.25 in W.C. to 1.0 in W.C. (they have been factory set to activate on a pressure rise of 0.25 in W.C.). The field adjustability makes these switches ideal for aftermarket residential furnace applications, electronic air cleaners and humidifiers.