Review on AGPtek® Professional Digital Tachometer Contact by Daniel Revlon

I didn't want to buy this because it was one of the cheapest items of its kind. But then I saw it being used in a "Project Farm" youtube review and it seemed to work pretty well. I've only been using it for a while, hence 4 stars. If you've read the manual, it specifically states that for accurate readings, it's important to have a high contrast between the background and the tape you're using as a marker. It's even suggested to wrap black tape around any shiny/shiny surface before using reflective tape as a 'marker'. This and even more expensive models work on the same principle. They all require a reflective surface against a high-contrast background to act as a trigger. As you can see in the photo, it doesn't matter what color the "marker" is as long as there is enough contrast. Red band, like other colors, works great on a black/dark background. The reason for the red tape is that the tape that came with it didn't stick very well to metal objects. I got fluctuating readings on any surface that didn't have enough contrast. Something else. There is no built-in protection against incorrect 9-volt battery installation. Otherwise you can damage the product. Look carefully and insert the battery so that the + and - poles are properly aligned. So far this has worked great. If this continues I will increase my rating to 5 stars. Good tool at a reasonable price