My father was not a car guy by a long shot. His favorite car saying is “I know where the ignition key and the gas nozzle go, that’s all I need to know.” But he came from a line of watchmakers, so he definitely taught me a few things about taking things apart and putting them back together…properly. And his favorite saying about tools is “Always use the right tool. And an adjustable wrench is always the wrong tool.”

I also inherited something—literally—from my father-in-law: these two Boos adjustable wrenches that I found in his basement tool boxes after my mother-in-law sold their house after his death. These goofy-but-interesting wrenches were one man’s attempt to do the ubiquitous Crescent wrench one better. The Boos wrench adjusts by turning the threaded handle, similarly to a vernier micrometer. Whether or not they’re a success, I can’t say. But they sure are oddly attractive.

Manufactured here in my home of Kansas City, the Boos Adjustable Wrench was invented by Joseph B. Boos just prior to World War II. It was manufactured according to one local source from 1940 through 1945. By its short run and the fact that the only ones I’ve found are located in the Kansas City area, I assume it was not a huge sales bonanza for the company.

So, how is it to use? Well, the clever mechanism has one clear advantage over a Crescent-style wrench: keeping a little rotational torque on the handle during use takes up any slack and keeps the jaws snugged tightly up against the nut or bolt you’re turning. That’s the good part. The bad part is that as they are adjusted, the geometry between the bottom and top jaw change, so that either the top or bottom one sticks out farther than the other. If the bolt or nut is tight up against an obstruction, this can be a problem. Also, they are really BIG jaws. It’s useless anywhere space is tight, really. And the top jaw is serrated, and the bottom jaw is smooth. So it will mar your bolt head, but still slip. To be fair, some of the patent drawings show two serrated jaws, but the Boos wrench can’t exert the clamping pressure of a locking wrench, so that still doesn’t make as much sense as two smooth jaws. The larger of my two wrenches is actually very hefty and sturdily made. The smaller one has a thinner, riveted sheet steel housing, rather than welded, and definitely feels gimmicky—like the wartime version of the Sears Craftsman Robo-Grip.

I have to agree with my father, adjustable wrenches will only get you into trouble, and there’s always a better tool to do whatever they can do. But these are so neat and unusual, and remind me of another man I so greatly respect, that I give them pride of place in my toolbox.