Author: Peter Thornton Really pleased with this product, which was a present from my children on father's day. Installation was simple and everything worked first time. I have had the product a coupe of months now and have installed it to its permanent postion once I verified everything was working. Instructions are very good and clear but don't go into enough detail on the various measurements and how they are calculated. Is the measurement averaged over the logging interval or the exact value at the start, middle or end of the period?