I had these for my track day at barber. I spent a day or two testing these out on some tires I didn't have mounted a few days beforehand. The warmers heat up incredibly quickly. I didn't have my temp gun on hand to check for offset, but these seemed to be true to what was displayed. I didn't find the instructions until my last day at Barber, but I was able to get the settings correct. Only giving 4 stars because the instructions seem to be for an older version, as they didn't really match up to the functions of the current version.