Milwaukee's Two-Beam Plumb Laser 2320-20 is compatible with the company's M12 12-volt cordless-tool batteries. It has a self-leveling range of +/- 4 degrees and an out-of-level indicator light, and provides accuracy of 1/4- inch over 100 feet. A low-battery light warns against power loss, and a 30-minute charger provides a quick charge. Price: $159. 800-729-3878. www.milwaukeetool.com.