This Angelcare Movement Sensor makes sure Baby's breathing for you, so you can get your much-needed sleep. The award-winning monitor set features a highly sensitive sensor pad that monitors the entire mattress and detects all her movements, even the slightest, whether she's awake or asleep. An alarm sounds only if absolutely no movement is detected for 20 seconds. The set also includes a regular nursery sound monitor and parents' unit. The nursery and parents' monitors have dual channels for optimal reception, movement indicators and alarm, low battery indicators, and for extra assurance, an optional "tic" feature that transmits sounds with every movement Baby makes. The parents' unit also allows Mom and Dad to see Baby's sounds with a lighted indicator. Both units automatically convert to battery power in the case of power failure. Power adapters included. Sensor works with any size crib mattress. Parents' monitor has a 200-ft. range. Sensor pad: 9-1/2Lx9-1/2W". Nursery monitor: 4Hx5-1/2W". Parents' monitor: 4Hx3W"., Movement sensor pad, nursery sound monitor and parents' unit, Sensor pad monitors entire mattress, Alarm sounds when no movement detected for 20 seconds, 200-ft. range, Optional "tic" transmits sound with every movement Baby makes