Those who opt for Babysense II, wants maximum security. The product has been well thought out principle and easy to use. The big advantage is that the device is powered by batteries and so inconspicuous and can be operated at any location, eg on a perfect Babybay or other mobile bed. For us the unit was 8 weeks running and we found that the unit chronicled movement signals, after we had taken out the little ones, and so also not triggered alarm. The most common causes - Betieb on an additional bed and transfer movements of the large bed, or an unapproved document for the mattresses were not available. The manufacturer (Amazon was no longer responsible) advised that the unit costs for checking (takes> 14 days) to send in. Our little one was on the 3rd month, so the period of höchtsen incidence of SIDS. The manufacturer was not willing to provide on demand but a replacement, or to send a unit in advance and was not very cooperative. So we had to buy another device and can repair the defective Babysense to it afterwards to sell on Ebay. This really is an unsatisfactory service of the manufacturer in a fault defective product. Shame on Audio Line!