The Stanley Intelli Tools TLM 50 Laser Measure can measure length with a single button, simple to use, both for taking simple measurements and for continuous measures. It has a compact, lightweight design with an ergonomic rubber casing. Its back lit display clearly shows measurements, even in dark areas. Also has an auto power off that saves battery power. Accuracy: plusmn; 3mmOperating Range: 15mPower: 2 x AAA batteries (supplied)