Your avatar brought back memories. My buddy bought a Metrinch set from Sears in the late 90s/early 2000s. We put that set to good use. Never actually got to try it on rounded nuts though. I do remember the sockets getting stuck on nuts sometimes. As a matter of fact that Sears store just closed it's doors last month.
Yep, my dad bought the 62 piece Metrinch at Sears around that time on clearance, we used it for a lot of stuff it was super convenient because there were still a lot of mixed metric and standard on cars of that era so you basically just took the one that fit and that was that. My dad bought my son the 76 piece a few years ago at Christmas, I’ve since got the 71 piece one. The design does work and it’s a shame they cost so much. The original patent expired but they got some other design patent which I think is due up this year, maybe knockoffs will appear. The imitations up until now have never been as good. I know the design has been knocked off overseas where the patent is expired but I was never able to get anyone to ship one to the US even as a one off. The largest issues With the design are the slop they have which has largely been remedied now if you use them with 90 tooth ratchets and they do sometimes get stuck. Usually if something is really seized once I get it free I reverse it so the socket doesn’t get stuck then remove the nut. The sockets themselves are very hard to break because the wall is thicker due to the way it grabs a nut.
They actually put a video up on YouTube last month so I wonder if they’re gonna do a relaunch to try and get another cash grab with the patent.

















