Detection distance: 1.Pin 30-60mm 2.64 model handgun 150mm 3.6 inch long knife 160mm 4.Diameter 20mm 5.Steel Ball 90mm Features: 1.Highly sensitivity. 2.Simple and convenient to use, no adjustment is required. 3.The detection distance will not be changed when the battery voltage drops from 9V to about 7V. 4.Low power consumption, can work for 40 hours continuously. 5.There is automatic and continues alarm when the battery is used up. 6.Switch on/off audio prompt function. With external rechargeable socket hole. 7.Has audio, Light and vibration handoff switch. 8.Charger voltage: 9V for AC; 10V for DC.(The charger shall be self-provided)