So I have 6" calipers and they are AMAZING. Too bad I can't share this review. I wanted to snag some handy little calipers from the same line as my trusty blue pair from 5 years ago. Unfortunately, something is wrong with the 4-inch version. First, I didn't realize that this size was missing a glide wheel. Not bad, I think I can get over it and it was my fault for not noticing that detail. The gliding motion is awfully hard. My 6 inch version glides like an angel, this shorty is like trying to take a dog to the vet clinic. He goes back to the box.