This is hands down the best tool for measuring cylinders. Very Important to note that you will need another micrometer or dial caliper to use this tool properly. This bore gauge is a dial indicator and can only measure a couple hundred thousandths, less then a 1/4 inch but has a range of 2 to 6 inches . It comes with pins and shims to measure diameters larger then 2 inch . You screw on the pin close to the size you need to measure. Then you set your dial caliper to the size you want to measure, lock it and slide it over the ends of the bore gauge. Zero the bore gauge dial on the maximum reading and it's set. Once this is set up you can quickly and easily see how far out of tolerance each measurement is. This tool is very easy to use and get a feel for. All you have to do is insert it into the cylinder and rock it back and forth on the wheels. The maximum reading is your measurement. Perfect every time and repeatable. I especially like the .0005 increments on the dial and the large spaces between the numbers make estimating .0001 easy. Another very important thing to note is that your maximum reading will be the smallest distance between the ends of the bore gauge. Since this is counter intuitive most people will get this wrong. When the dial only makes it to -.001 it means that the measurement is +.001 too big and when the dial goes to +.001 it means that the measurement is .001 too small. I have always had really good luck with dial indicators, they seem to hold up very well to being abused. I have bumped and banged this one a bit and it works perfectly.

This is my second tool of this model. I sold my first one thinking I'd never need to measure cylinders again, having bought a new car, but of course I did... This time I'm keeping mine.

The price is very reasonable, and the accuracy is phenomenal, if you learn to read it right. Very repeatable. With a little finesse you can calibrate it from calipers or a micrometer. You just set the bore gauge between the jaws of the calipers, and wiggle it carefully until you get the highest possible reading consistently. That's your baseline dial position for that exact caliper measurement, then you measure the actual bore and it gives you your piston to wall clearance. If you do it a few times and your results are repeatable, you know you're dead on.

This is the only gauge you need on a small block chevy, as it measures cylinders, mains, rods, and cam bearings. The only thing you can't measure is wrist pins :) On smaller engines with journals smaller than 2" +- a few tenths (mitsubishi 2.0 rods, for example, if I recall correctly) you won't be able to fit this tool. There's a smaller version for that.

I've eyed more expensive name brand bore gauges, but honestly, this is so accurate, it's all you need. In reality you can consistently read with accuracy down to 0.0002, which is plenty exact for engine work.

I love this gauge! So much easier to use then the old inside expandable gauges which you had to measure with a caliper for each measurement. This gauge is easy use to check taper, oval and overall wear, and to compare cylinders. The only tricky part is setting it to the right calibration before you begin measuring. You use a caliper and all three of your hands. I have only two and had difficulty getting this done. After setting the caliper to the ten thousandth, you have to hold both bore gauge anvils against the caliper blades while setting and locking the bore gauge dial at the same time. Once you figure out a way to do it, you are home free. I found that by watching the needle on the dial indicator while I worked the anvils into the correct position, I could then put the caliper down and set the gauge to the reading I had observed. After repeating this about three times, i got the bore gauge set almost perfectly. You'll see what I mean when you get it in your hands Once it's set, it's a joy to use.

Overall great wuality tool but it was missing a piece and was supposed to be brand new

Very nice gauge for the cost. It takes a bit of time to figure out how to get the most out of the gauge but when used properly it's able to give very accurate readings. You need a good inside micrometer set to get the size in its rest position because the printed sizes are off a few thousands of an inch. Once you get the resting size; the actual gauge reads very accurately in action and when subtracting the reading from resting size I was able to verify its high accuracy compared to a couple other gauges, telescoping gauges and mics. I am building a race engines so I am just using this to verify the machine shop did everything properly.