I'm an old gear guy (53 years old) and have restored about dozens of engines over the course of a year "I like this t-hole, shackle gauge set and micrometer set, mainly for its affordability. I have had access to Starrett micrometers in the past when measuring pistons, cylinder bores, connecting rods and main bearings. This set is of inferior quality to Starrett , but I thought it was pretty good I've found you pay four to five times as much for Starrett gear but all I really do now is measure pistons, cylinders, connecting rods and main assemblies to get a rough To get estimate to see if I'm going to bore the cylinders out .020."crankshaft backwards by .010 or vice versa" etc. I let the local workshop work its magic where they super d super microns that are critical to their work. So unless you're getting into a machine shop, why spend big bucks on superior gear just for a first estimate? I found these mics quite satisfactory. Of course if you want to measure cylinders you need an inside measurement so I also bought a set of telescoping, snap and T gauges. They worked well, very happy with both kits. I also bought a set of cylinder bore micrometers which use a traditional dial indicator where you don't measure the actual bore so much as the difference in bore diameter to determine if the cylinder is tapered or whiskey. Barrel to cylinder etc. I found this somewhat useful, but the micrometers mentioned above with a telescoping clip-on T-gauge set were more useful. Just my two cents.