What's this for?

[skylab]

found at the flea.  Used on a square nut  can't read the writing very well.

[Billman49]

Possibly a bed key - used for tensioning the spring sub-base on old wooden framed beds...

[OilyRascal]

I have seen the same (square nut t-handle design 6" long) used as a key to a lock on a side-box of an industrial truck bed.

[jimwrench]

 The Owsley Bros had a patent on the Acme twist handle wrench. Don't know if this wrench was made by same company.

[rusty]

Owsley Bros was indexex under wrenches, and 'general merchandise', so it's plausable at least.

The wrench may not be for anything in particular, square T-handle wrenches were a standard wrench type once upon a time, you just don't see them much these days...

[Lump]

I have seen wrenches like this used for turning valves on and off, such as gas valves on cylinders, etc.

[amertrac]

looks like a tool to open groun level valve boxes like natural gal,water or gasoline   

[Nolatoolguy]

I would be willing to say its a sillcock key.

Basicly used for opening and closing comerical pipe fittings.