Babysense has two very sensitive sensor pads which are placed under the baby's mattress, and a high speed microprocessor control unit. The control unit alerts you with a loud alarm if it does not detect any movement for 20 seconds or if it detects less then 10 micro-movements per minute. Even the slightest body motions are registered as movement.

Features:
Green light flashes to indicate movements
Red alert alarm light
Low battery indicator light
Suitable for infants up to age one
Needs no direct contact with baby
Easy One-button Activation
Activation button safely cover
ABS plastic exterior
Powers by 4 AA Standard 1.5 batteries

Not a medical device. It monitors and alerts, but cannot prevent any type of distress. The purpose of the device is to alert you when stopping or slowing of movement. Paid $300