Review on TM8812 Ultrasonic Thickness Gauge: Accurate Measurement from 1 to 200mm (0.05-8-inch) by Brian Whitmore

Purchased to check core misalignment on cylinder walls and wall thickness when porting cylinder heads. The supplied measuring disc measures very well, but is out of place on cast iron and painted sheet steel. The good thing is that it looks thinner than it really is, giving you some wiggle room. Maybe my results will improve as I improve, but for example my 6.5 diesel block has a baffle thickness of 10.25mm. The machine says the thickness is 10.1mm. Just in case, I've tried all the settings, but it never gets more accurate. For the price compared to what a real sonic probe costs, it's better than guessing like I usually do.