DIY. With necklace, Wireless type. Press panic button if needs help, the main unit(control panel)will go off siren and auto-dial out the phone number for help. It features panic help for 24 hours protection. Widely used for older, kid, bank, financial dept., panic thing...etc. Easy to carry.

Specification
1). Wireless frequency: 433MHz OR: 315MHz(other optional)
2). Working voltage: 12 V. 23A
3). Alarm current: I2≤ 15mA
4). Transmitting distance: <150m(in open area), indoor: 30~50m
5). Operated condition: Temperature -10 -60degree, Humidity ≤ 95%
6). Weight: 0.05 kg