[Milsurplus] Proper size Allen wrench for APR-4 tuning unit frequency knob?

[Jack Sullivan]

I just received my 2 missing APR-4 tuning unit knobs but none of the set of wrenches I bought at Dayton some years back seems to do the trick. My neighbor has a box filled with every conceivable size of hex key but I thought I'd ask before starting that project.

As a side note, the TSA at the Dayton airport inspected the set of wrenches as I was leaving & seized the 3/8"as that reached the minimum criterion for a non-allowed weapon.

Jack