I'd speculate on a bicycle or motorcycle wrench. The kits on both needed to be compact, since there was precious little storage space. I own (or used to own...I need to look to see if it's still in the wrench drawer) a Jawa (CZ) motorcycle wrench that has the two needed feeler gauges riveted at the center point of the wrench (points and plugs, probably - the motorcycle from which it came was a two-stroke, so no valves to worry about).