Okay, I have a high end carpentry shop and we often have to do layouts for architects. They always provide layout drawings with exact measurements down to 64 inches. So I know they calibrate layouts. All the calipers I've had always show different numbers when we calibrate stock. Even if it's a piece of plastic that we know is there. So when I was looking for an accurate caliper, I read the reviews and settled on this one. The first thing that struck me when I took it out of the box was the weight of this caliper. Is surprisingly solid and heavy in the hand. I can immediately say that the quality is excellent. I then tested it against the box the spare battery was packaged in. Yes, this device came with a spare battery, which was very nice and unexpected. It is calibrated the same in every range along the 0.028 inch edge. I was and still am very impressed with this product, it is by far the best caliper I have ever used. I'm buying five more so everyone in my store can have one and when they get here I'll throw away any others that are lying around my store. Half of them stopped working altogether. This is a great purchase if precision is key to what you produce.