Advantages of Bosch GRL 500 HV + LR 50 Professional Rotation laser The first rotation laser with theft protection for all levelling work Theft protection: an alarm is triggered if the GRL 500 H/HV is moved without the LR 50 Professional during operation. Calibration reminder: automatically indicates calibration requirement. Slope function: enter slope values directly and precisely using the LR 50 Professional keypad. Sleep mode: When the tool goes into sleep mode, all settings are saved and the theft protection and the Anti-Drift System remain operational. Centre Line button: automatically aligns the laser beam with the centre of the receiver and measures the slope value. Simultaneous charging: the Li-Ion batteries in both components are charged together in very little time. Line Control: align the vertical line as desired in vertical mode using the arrow buttons. Anti-Drift System: prevents levelling errors in the event of shocks or vibrations. Relative height display: distance between where the laser beam hits the reception area and the centre of the receiver.