I wondered if this was just a gimmick - just another way to do something you can already do ten other ways. It's not just a gimmick. While it competes with many other ways to clamp right angles, it is unique in doing both the alignments and clamping all with one screw. My second doubt was how strong it could actually hold given it only grabs "the edge". I was pleasantly surprised to see that it was VERY strong at clamping. The depth of the channel for clamping the wood is as deep as the face of most clamps, and deeper than the thickness of many other corner jigs. And, wow, those are not hollow pieces of metal or plastic. All the pieces are solid aluminum milled from a single ingot of aluminum block. This sucker is heavy and strong.
So why use it? There are lots of other ways to clamp corners. As I was fiddling with it the first time I felt it was awkward to align the wood and find the screw and make sure everything was going right. But I realized that it was a short learning curve. Instead of holding a right angle jig and two (or more) clamps in position while tightening the clamps and making sure they didn't rack the corner apart in the process, this Box Clamp makes it a very quick and easy two hand job. One screw is only used to set the width of the material to be clamped. You do that once ahead of time and you're set. So to clamp a corner (any joint) or a midpoint shelf all you do is place the wood in the box clamp channels (or put the clamp on top of the wood if you need it there, and tighten the one screw to grip both pieces of wood with a nice tight, wide grip. No slipping or nudging or multi-step bar clamp adjustments. Excellent.
One thing that takes getting used to is there is no knob to turn to tighten it. That annoyed me initially, but I eventually accepted that a knob would get in the way of most glue-ups, and it was worth it to grab my long-neck, T-handle allen key to do the adjustment (although it does come with a regular "L" shaped allen key). BUT... If you use it freehand instead of on a bench (so that the bottom of the clamp is available, Woodpecker provides an alternate bolt and knob-style nut to switch tightening to the back/bottom, clear of the wood and tightened with a traditional knob.
One last thing that's not clear in the photo is that there are three countersunk holes in the base if you chose to screw it down in a jig set-up. I'll post a couple of additional pictures shortly. In short, (too late) Woodpecker has delivered yet another super high quality, well thought out tool. My only regret is that it only handles up to 1 inch wood thickness - no picture framing with this guy. Five stars!
I was shocked by the price, but once I got the clamps I was amazed at the quality of the clamp. Not realizing the power of the clamp, I BUSTED my first board with it. Tight fitting joints each time, why did I not order earlier? The only thing I changed was the knobs; I just didn't like the standard one, and changed to Multi Knobs by Woodpeckers, also used a long reach hex wrench, not the short stubby that came with it. Much better, easier on the hand and I believe you can get more torque than the standard knobs that come with them. My only wish is that they would make a larger version. You would do yourself a great service by treating yourself o these clamps. Buy these be and happy to know you're buying Made in USA, and supporting American jobs