Treadle Kit, Pneumatic. Outdoor Enclosure (NEMA 4/12), Includes 10 feet of signal hose, outdoor air switch, and hose plug, OPEN only (all operators), or SAFETY only ( operators with type B2, C2, T, T1 or TS control wiring) after vehicle passes over treadle hose. The weight of the vehicle on the treadle hose activates a pneumatic switch which sends an open signal to the door. Requires a 2-wire connection to the operator but does not require power to function.