The new Bosch is awesome in this regard. I've thoroughly tested it to all the tricks. The reproducibility of the measurement is breathtaking (identical to the last millimeter!) And the precision is definitely as accurate as the measurement with a yardstick. The device gives three decimal portion behind the meter point - the last digit is then the millimeter. I was impressed that the device can not even carry glass sheets astray. In our triple glazing he reproducible taken the outer pane as a reference. The PLR 15 by the way measures only distances and can not calculate areas or volumes dimensions internally. Who wants that, you need a calculator or must be good at mental arithmetic. But there is another model, which can also count internally, says at least the manual. The unit is equipped with its 10 x 3.5 x 2 cm very handy and with 76 g (incl. Batteries) very easily.