I really like this tester. Saves me from having to bend over my desk to see an indicator or edge finder. Accuracy within 0.0002 Based on readings from a recent Mori mill. I bought an ER32 collet to insert. The runout was 0.001 and was easily adjusted to 0.0001. The shaft on this device is approximately .872 in diameter. Not .75 like the dial model. Therefore, you must use a collet.