Features: 1.Blue Backlit: The screen of this LED handheld tachometer will display the maximum measured value with a blue backlight for easy reading, offering great convenience. 2.Easy Operation: This propeller speed tester is easy to use, just turn on the switch, select the number of propeller blades, and aim at the rotating propeller at a distance of about 2 to 3.9in to start reading. 3.High Accuracy: This digital tachometer features slight error and high accuracy, which is suitable for RC airplane, duct, propeller speed test of propeller. 4.Durable Material: This RC drone tachometer adopts premium ABS and electronic components material, sturdy, durable and long service life. 5.Comes with Lanyard: This RC digital tachometer comes with lanyard, light weight and easy to carry. Simply hanging on a hook or shelf, providing convenience. specification:Item Type: LED Handheld Tachometer Material: ABS Application: Suitable for Drone Propeller Battery: CR2032 x 1 220mAh Inbuilt Battery: CR2032 x 1 220mAh Working Mode: Photoelectric Highest Reading: 99,999 Display Mode: LED Number Of Propeller Blades: 2 to 9 Automatic Shutdown: 1 Minute Without Signal Backlight Color: Blue PackageList:1 x LEDHandheldTachometer 1 x Battery 1 x Lanyard