Feature
1.Highly sensitve.
2. Simple and convenient to use, no adjustment is required ;
3. The detecton distance will not be changed when the battery voltage drops from 9V to abou t 7V
4. Low power consumpton ,can work for 40 hours contnuously
5. There is automatc and continious alarm when the battery is used up
6. Switch on /off audio prompt functon
7. With external rechargeable socket hole
8. Has audio, light and vibraton handoff switch