The NI 150 Heartbeat Sensor was developed by Noi Industries. The sensor acts a sort of advanced radar, capable of detecting human beings.
Developed originally to attach to their firearms, Noi Industries later made them portable. The devices can detect nearby heartbeats up to three hundred meters way, though it isn't able to distinguish man from animal. The device can however distinguish friend from foe if friends are carrying sensors or some sort of tag, as the 150 is able to detect the signal and color nearby readings blue rather than the unknown red.