I have been using GN W+ 3/8" extensions a long time since before this product.
Not a prestigious brand but despite frequently misusing them none have ever failed. They are all I kept actually. I was looking for a reason to upgrade but these refuse to give me one.
I even considered a copycat version made from an impact extension but just never had to put a wrench on an extension yet.
My afterthought is it was a solution looking for a very specific problem. Not bad, just not a widespread need.