If you’re in the barn, greenhouse, or garden, these wireless radio operated systems will let you know when you have company. Set the transmitter model in any direction — it emits an 80 ft. invisible beam and sends a signal up to 500' back to a ringing bell or turns on lights, activates a siren, starts a telephone tape dialer, etc. 120 vac receiver has on/off switch, 4" x 4" transmitter uses 9V battery. Rubber hose drive alert activates the same signals when a vehicle crosses a 25' 3/8" hose.