VISION Active-IR shock sensors use a tiny infra-red emitter, receiver and suspended reflector to detect impact. Even the smallest movement of the reflector is sensed, and intelligent analysis of the movement eliminates false triggers.
Like the 318-052 shock sensor, the IRS-2 eliminates falsing without sacrificing sensitivity; but the IRS-2 improves on the 318-052 by offering lower power consumption and 2 independent sensitivity adjustments: Warn Away trigger & Full Trigger. Dual adjustments allow finer control over when the sensor should trigger.

Active-IR 2-Stage Shock Sensor, with Dual Adjustments