Item 18-946 Dual-Beam design for greater stability Auto Gain Control Circuit apply to any environmental conditions (rain, fog, snow etc.) Dual infrared beams available in 60m (outdoor) / 180 (indoor) Separate receiver LEDs for beam alignment, received ligh level, and alarm, transmitter power LED indication provided Build-in viewfinders for optical axis adjustment. Both horizontal and vertical adjustment are provided at the receiver and the transmitter with alignment and signal level LEDs at the receiver to confirm optimum adjustment Mist hung preventing cover design. Tamper protected Surge Absorb Circuit Prevents the sensor from damaging by thunder Blocking time adjustment is provided for specific target movement rate detection