Very important: The Huepar laser receiver is only suitable for the Huepar laser level PWM ：1:1 Frequency ： 10 KHz Display ： Three-sided LED display Leveling accuracy ： ± 1,5 mm (± 1/17 In. ) Laser reception window width: 20 mm (4/5 inch) Laser reception window height ： 20 mm (4/5 inch) Working distance ： 60 m (200 ft) Working time ： 70 hours Automatic shutdown (without signal detection) ： 8 min Power Source: 1*9V Dry Battery Items in the package: 1 * Huepar LR-6RG laser detector 1 * heavy-duty clamp 1 * 9V dry battery Set the laser level to Pulse (Outdoor). I made sure the laser level and receiver windows were clean. Recheck the batteries in both devices (laser level and Huepar laser receiver). Make sure that your laser level can be used in conjunction with the Huepar receiver. Precise optical signals Move the detector according to the direction shown: Reference lower than laser beam - upward movement Datum higher than laser beam - downward movement When the reference is compatible with the laser beam - the LED indicator glows green Buzzer Remind The beep signals the detection of a laser beam: Slower beep means upward movement Fast beep means downward movement Three-sided LED displays provide clear LED hints on three sides LED displays on the front LED displays on the side LED displays on the back Built-in dome and handle The LR-6RG laser detector comes complete with a compatible rod mounting bracket. The built-in bubble level provides an additional measure of leveling accuracy.