I have a Starrett 445 set with rods up to 9" plus spares, a B & S smaller set, and a Starrett 463 mic. head with a small accessory depth foot on it. I use the 463 head for most simple work, and it fits into tight places and is smooth and easy to get a good feel with, the bane of depth mics. To me, smooth and calibrated rules. With my 0-9" set, purchased used and with new Starrett rods having been added, I have no idea if it is properly in calibration for every rod, so I calibrate it for each different one I need to use and then mark it as being calibrated. About the only advantage to buying a quality new set is that it is likely properly calibrated. A cheaper or used set will need to be tested and possibly calibrated for each rod length...