No. of H Beams 4 No. of V Beams 4 Plumb Laser ok Tangent Screw ok Wave Length 635nm Operating Temperature -10C ~ +50C Working Range Indoor: 10m; Detector: 30m Self-leveling Method Electromechanical Leveling Leveling Accuracy 2mm/10m Compensation Range 2 Power Supply 1.5V AA batteries X 3