I had high hopes for these devices, they turned out to be just what I needed. I am an experienced electronics engineer, I connected them exactly according to the instructions. The first unit appeared to work, but failed within minutes of being connected to my dyno. Blank display, no work. So I replaced it with a second unit that worked great on my dyno for a day, but once installed in the chassis it didn't work like others have. Blank display, no action. My experience seems to be common among reviewers. These cheap units are cheap for some reason, very poor quality, they are very unreliable. Save money by spending a little more and buying something that works. You will only throw away your money by buying them.