This product is mainly used for object acceleration and velocity measurement, individual users can use it to measure the design speed of all kinds of playthings. Aluminum alloy, stainless steel material, support rod, velocity measurement, energy measure, speed energy, looking through record and view average. This product is made by DIY, with concise and practical, accurate and durability for the purpose. It is mainly used to learn and experience the ability of the SCM to process data at high speed, and it can measure the flying speed of projectiles. Such as: table tennis, badminton, bow, arrows, physical acceleration experiment, projectile free fall experiment, playthings speed measurement, children's soft playthings, etc. The core components are industrial-grade package, stable performance, small error. This product for the speed of 1 to 999.9 meters per second projectile with accurate speed. The utility model has the advantages of large effective induction area, convenient use and high sensitivity. Strong adaptability to ambient light, indoor and outdoor can be used during the day and night. Can save 20 sets of data, you can see the average. Voltage: DC 6V Battery(not included): 4 * AA battery Working Temperature: -30 - 60 Accuracy: test error 0.5% Measuring Range: 1-3000 M/S(FPS range 30-9000) Standard three tripod can be installed This product does not contain tripod and batteries Instructions for WIFI version: 1: Install the battery 2: The external round hole plug needs to be inserted into the machine (USB power supply) 3: Open the mobile phone WIFI settings, find the HT-50, the connection password is 8888888 4: Open the browser and enter the URL 8.8.8.8 to view the data on the mobile phone Notes: This product is infrared radiation type, the light source has been integrated in the machine, no external light source. Recommended for use in low light environments. The darker the ambient light, the better the machine performance. For outdoor use and strong light conditions, a light shield must be added. When measuring the speed of the projectile with higher speed. Please take appropriate protective measures. In order to avert the rebound of the projectile after hitting the machine and causing damage. Observe the marking on the left and right sides of the light bar when installing, and the strip with the light is facing down. Color: As shown Material: Aluminum Stainless Steel Package Contents: 1 * Speed Meter 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.