The Graco iMonitor Vibe with 2 Parent Units features 100% Digital Technology and Exclusive Vibe Technology. 

Secure digital technology delivers optimal clarity, performance and privacy, and the 900MHz frequency means no interference from phones and electronics. 

The exclusive Graco vibration notification technology allows you to feel baby's call in addition to hearing it.  With an extended range of up to 2,000 feet, you'll have plenty of room to roam and still be able to keep tabs on baby.