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. 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. High Accuracy: This digital tachometer features slight error and high accuracy, which is suitable for RC airplane, duct, propeller speed test of propeller. Durable Material: This RC drone tachometer adopts premium ABS and electronic components material, sturdy, durable and long service life. 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.