Well, I bought the Craftsman Industrial Professional USA made 12 piece offset box end wrench set. It's the same as the NOS USA - Armstrong made Craftsman Professional offset box end wrench set, with the difference that it says "Industrial" instead of "Professional". Before I bought the set online, I had gone to Sears and compared the Chinese metric set (using the 10mm as a comparison) they had on the shelf with the 10mm USA professional open stock one on the shelf. After holding up the USA made 10mm one to the Chinese made 10mm one on the package that says "Craftsman Professional - Full Polish" (made in China ones), there was a noticeable difference in the size of the box end. The USA one is noticeably "thinner" (width-wise) than the Chinese made one. The Chinese made ones "should" work ok I guess for the most part. However, the USA made 10mm one may come in handy where there is a clearance issue, as well as I'm thinking the quality of the steel and tempering in the USA made one may make it stronger and that may be the reason why the USA one is made thinner...
On other notes, I also have a Snap On set. (I got the Craftsman Industrial set to use at my parents place since I'm not going to use them that often, other than when I work on their vehicles). I also compared the 10mm, 11mm, 3/8, 1/2, and 9/16's of both the Snap On ones and the Craftsman Industrial ones. There are some key distinctions between them. The Craftsman Industrial 10mm and 3/8 were noticeably "shorter" or "thinner in height" on the box ends themselves compared to the Snap On ones. I'm thinking approximately 3/16". So, the Snap On ones were "thicker" or "taller in height" compared to the Craftsman Industrial ones. However, the Snap On ones of those had thinner heads when comparing the "width" of the heads.
Whether this is an important detail or not depends on the clearance needed. Vertical clearance, the Craftsman-Armstrong Industrial 10mm and 3/8's would give a little better clearance. If there is limited clearance side to side, the Snap On ones would give you a little better clearance. The 10mm Snap On one was about 1/4" - 3/8" longer (I don't think this would make much difference) as well. One other important distinction between the Craftsman Industrial wrenches and the Snap On's are that the Snap On ones "grip" better or "grab" better.
What I did was put my finger in/on each of the box ends and turned the wrenches while my finger was at the wrench opening to get a feel for how how it would be when it turned a bolt. I also held the wrench stationary and would turn my finger at the box ends of each Craftsman wrench and the Snap on wrenches. The Snap On wrenches would again "grip or grab" better. It's as if the broaching of the Snap On wrenches is distinctively different. The kicker was when I was able to put my index finger in the Craftsman Industrial 9/16" wrench and the wrench turned around the finger as if it was slipping around the finger quite easily. I then did the same thing with the Snap On 9/16". My finger was noticeably tighter in the Snap On 9/16" than the Craftsman. I then proceeded to turn the wrench and let me tell you, this wrench would have broken my finger if I turned the wrench the same way I did with the Craftsman. It gripped/grabbed my finger and no matter which way I would turn the wrench, it grabbed and turned the finger without any slippage whatsoever. I only turned the wrench about 1/8" each way to realize the difference between the wrench brands. The Craftsman 9/16", I could turn the wrench around my entire finger and not have to worry about it breaking my finger. This to me is an indicator as to which of these wrench brands would take a bolt off without worrying about rounding off or stripping the bolt or wrench. The Snap On obviously...
If you're not going to be using the offset box end wrenches much, the Craftsman Industrial Professional wrenches should work just fine generally speaking (in most cases). If however, you have a rusted bolt or a bolt that is rounded already, I wouldn't take a chance with the Craftsman and just get a Snap On one... There is a reason why Snap On says "There is a difference". It's not just the price either, but their tools simply work better in comparison to other brands. In this case, the Craftsman-Armstong Industrial.
I posted this to let others know my experience with both so whomever can decide which brand of offset box end wrenches to purchase depending on how much you'll be using them. Use/cost factor... I hope this helps. I don't know if anyone has done a similar type of test/comparison with SK, MAC, Cornwell, Stahwille, etc. It would be interesting however... I imagine Matco maybe the same at the Armstong-Craftsman ones depending on the wrenches (combination, offset box end, etc. Maybe not however as some of their stuff is made in Taiwan).
