This was very good value considering the original list price was around £50. It works well and gives reproducible readings within the quoted +/- 5% accuracy, which is normal for an ultrasonic measuring device. My only criticism is that unlike more recent ultrasonic measuring devices, it doesn't have a laser locatng beam, so it is hard to tell which part of the opposite wall it is aimed at.
Was reasonably satisfied with this product until it was checked against a tape measure where there was an average error of 25mm. Not great when measuring up for carpets.