CST/berger RL25HV Horizontal/Vertical, Interior/Exterior Rotary Laser Vertical Beam Feature: for easy and precise layout of 90-Degree corners and plumb applications- Both horizontal and vertical beams are self leveling Glass Enclosed Top Housing: for maximum weather and environmental protection Full Selection of Beam Visibility Enhancements: Variable speed (0,150, 300, 600 RPM) and Variable scan angles (10, 25, 50 Degree) More Runtime-Up to 85 hours of runtime with (3) D-cell Alkaline batteries Battery Level Gauge: Alerts you when a battery charge is low Class IIIa laser product, &lt;5mW power output