The Laser Dimension Master II (3339) from Calculated Industries is capable of fast, accurate indoor measurements from 20 inches to 50 feet with 99.0% accuracy. It's easy to use: just aim and press a button, when the unit beeps, you've got a measurement. It works by using a narrow ultrasonic beam to measure at the speed of sound, even in areas with furniture or fixtures. Great for real estate agents, interior decorators, appraisers, estimators, remodelers and designers.