This handheld speed measuring instrument measures object acceleration and velocity accurately, with a range of 1-999m/s. Mini, easy to carry and operate, with a semipermeable half-reflecting LCD screen. You can switch between Chinese and English language, record up to 160 groups of data, and charge with a USB cable in 1 hour for more than 10 hours of use. Suitable for learning and measuring the high-speed data processing ability of single-chip microcomputers, and measuring the flight speed of various objects. Features: 1. This product is mainly used for object acceleration and velocity measurement. Individual users can be used to measure the design speed of all kinds of shooting playthings. 2. Mini size is easy to carry. Simple and easy operation. 3. Handheld type speed measuring instrument, with high accuracy measurement, 160 groups datas will be recording. 4. Measuring speed range: 1-999m/s. 5. Metal surface and fully closed, this speed measuring instrument will not affect by the sun and air current. 6. High accuracy, with accurate measurement data. Humanized design unit conversion function. 7. Mainly used for learning and experiencing the high-speed data processing ability of single-chip microcmputer and measuring the flight speed of various things. How to Use: LCD backlight setting, you can set constant light or long out. When you set as automatic, the screen will light out after 10 seconds without operation. With automatic shutdown function. Charging by using the USB line, charging time is about 1 hour then you can use more than 10 hours after full charging. The red light bright in the charging and the blue light bright in full charging. Built-in overshoot protect, overdischarge protect, short-circuit protect, etc. With holders and pinboard package. Without using the pinboard, the using pipe diameter range is 20-31mm, less than 20mm you can add the pinboard or tie on the pipe. Using the pinboard, the using pipe diameter range is 16-43mm, less than 16mm you can add the pinboard or tie on the pipe. Included three keys, first is switch key also is confirmation key, second is up key, third is down key. With Chinese and English switching function. You can change the language by your self, press the down switch after starting up, and find the language line and press the confirmation key. Using semipermeable half-reflecting LCD screen that you can see clearly in the darkness or in strong light. Specifications: Working Voltage: 5V Measuring Pipe Caliber: 10mm Accuracy: test error less than or equal to 0.5% Measuring Speed Range: 1-999m/s Cell(built-in): 1 * 5V 300mAh Lithium Cell Item Size: 73 * 44 * 33mm / 2.9 * 1.7 * 1.3in Package Size: 100 * 60 * 50mm / 3.9 * 2.4 * 2.0in Item Weight: 85g / 3.0ounce Package Weight: 120g / 4.2ounce Notes: Please allow 1-30mm error due to manual measurement. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Package List: 1 x Speed Measuring Instrument