The panel is mainly composed of digital display tube, function, key and LED indicator. The function key is the micro-touching button. Four sides of the air design, to effectively ease the impact of testing time. Improved stability and accuracy. Display and the operation of the button in front of the operation and to see the test data are very convenient. Mini size is easy to carry. Simple and easy operation. High accuracy measurement. As the device with high accuracy and clamp rail, and fixed equipment after the path every time are the same, and with the guide rail can be made with the mining model in parallel, so the measurement result error is small, small fluctuation dynamic error. Function is more abundant. Not only can measure the speed, but also can measure the kine-tic energy, at the same time can record up to 40 groups of speed and the 40 group of the kine-tic energy value. Multiple power management and protection. The lithium cell has the function of over charging, over discharging and short circuit protect, and the integrated intelligent shutdown and low power shutdown function. Note:This product is a clamp type speedometer, which must be clamped on the tube for testing, and cannot be tested against the clamp. The speed can be measured only when the is flying in the middle. Mainly used for learning and experiencing the high-speed data processing ability of single-chip microcmputer and measuring the flight speed of various things. Such as: table tennis, badminton, and so on. Core components are industrial-grade encapsulation with stable performance and small error. Working Voltage:DC4.2V Accuracy:test error less than or equal to 0.5% Measuring Range:1-999m/s Cell(built-in):1x3.7V 450mAh Lithium Cell Working Surrounding Temperature:-10 - 60 Speed Measurement Range:1-999m/s Energy Measurement Range:1-800J Weight Input Range:0.1-10g Speed Record:40 group Kine-tic Energy Recording:40 group Item Size:130x80x50mm/5.1x3.1x2.0in Item Weight:145g/5.1ounce Due to different product batches, the appearance , which does not affect the use. Colour:Black Material:Aluminum Plastic Package Contents: 1 * Speed Measuring Instrument Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.