Along these lines, Crescent recently introduced a model of their famous adjustable wrenches that has a vice-grip like locking fixture so that when you get it adjusted to the size you need, you can lock it so it won't loosen up as adjustable wrenches can. In effect, it makes the adjustable wrench an open end wrench. Unfortunately they only make it in the 10 inch size and it costs 25-30 bucks. I would be willing to pay the price, but I would really want a 6" one to keep in my seat bag. I wouldn't carry a 10", and at home I have ratchets and open/box end combos, SAE and metric, so I seldon have to resort to an adjustable.