I have one from HF. Use it all the time for various reasons.
Wished I'd have had it when we were racing stock cars. The real way to tell how your chassis is working is by checking tire temps immediately after a race.
RF should be hottest, followed by RR, LR, and LF, in that order. Can also optimize tire air pressure by comparing readings on the outer edges of the tire to the center. Can check camber on the front wheels by checking the temp across the face of the tire, etc.