Shock resistant, doesn’t break if dropped to the ground. Sound alarm, red LED light and vibration indicates the detection of metal. Self-calibrating, no need for periodic sensitivity adjustments. Optional rechargeable battery kit. Adjustable sensitivity. Detection distances: pistol or six inches knife - 180 mm, 25 cent coin - 75 mm, pin: 30 mm. Specifications Dimensions: 375 x 77 x 26mm (L x W x H) Weight: 220 g Frequency: 25 kHz Power: 9V (6F22) standard or rechargeable battery (optional) Operating temperature: -10 °C to +55 °C Relative humidity: 0 to 95% without condensation