1、WORKING PRINCIPLE It is used to transmit ultrasonic waves to the measured object, and then calculate the ultrasonic round trip time to determine the measurement distance. 2、MULTIPURPOSE It is suitable for home decoration, calculation of area and volume when buying air conditioners, property agents or construction workers who need to quickly measure the area of ​​rooms and rooms. 3、WIDE RANGE OF APPLICATION It is very suitable for indoor and outdoor surveying, building surveying, woodworking surveying, interior decoration and so on. 4、CLEAR MEMORY FUNCTION This function allows you to quickly delete all stored measurement values, and the operation is simple and quick. 5、EASY TO CARRY With its small size and light weight, it can be comfortably placed in your hand and easily placed in your pocket. 1 x Range Finder (Battery Not Included)1 x English Manual Item Type: Range FinderMaterial: ABSWeight: Approx. 105g / 3.7ozProduct Size: Approx. 15x 5.5x3cm / 5.9x 2.2x 1.2inBattery Parameter: 1 x 9V Battery (Battery Not Included)Measuring Range: Approx. 0.5~18m / 1.6- 59.1ftError: Five ThousandthsResolution: 0.01mMaximum Measuring Distance: Approx. 18m / 59.1ftMaximum Sum of Distances: Approx. 180m / 590.6ftMaximum Calculated Volume: 1800.0 Cubic MetersTransmission Frequency: 40kHzWorking Temperature: 0°C ~ 43°C