UM6500 Handheld Digital Ultrasonic Thickness Review

The resolution appears to differ by about .040" when measuring a .907" cast iron main bearing cap as a test before checking the Chevy small block cylinder bore thickness. I've tried all three iron settings, C02, C10 and C11, but C10 gives the closest reading of 0.866" with actual measurements of 0.907" on Mitutoyo digital calipers. I'm getting realistic readings of around 0.266" for cylinder bores, but without the 5mm gauge block that should have come with the gauge I can't trust that. It was…