Obviously it's no replacement for being watchful, but it can help if you happen to be momentarily distracted. The pressure mat detects when even the tiniest of feet have crossed the door threshold! It then sends a signal via a transmitter to activate a vibrating pager or a flashing/audible receiver that you can carry around the house with you, or have by your own bedside at night.
It also has other uses - for example, to carers to alert that a patient has got out of bed or its original use - for deaf and hard of hearing people, to alert them to someone entering or leaving the house. Particularly relevant with Deaf Awareness Week (7th - 13th May) coming up.
Find out more at the RNID shop