Weird wrench

This last weekend, I went to a garage sale and picked up a woodworking vice (light surface rust) for two bucks Australian (about US$1.50). I also picked up this brass-looking wrench (the camera's flash doesn't show the color correctly) for a buck (US$0.75). Also two pulleys; and I fished a black plastic Black & Decker case for a cordless drill out of the skip out in front of the house (clearly, they were sorting through the garage and tossing a lot).

Anyone know the intended use for this thing? Clearly, the design is functional in some manner. Is the brass-ness to prevent sparks (e.g. for working on flammable items)? Has ''GEE-JAY'' stamped into one side.

The woodworking vice, BTW, says it's six inches, ''MADE IN AUSTRALIA'', and has a brand name of ''CARTER''. Don't know if that's a good brand or not, but the screw turns just fine, I've been needing to buy a WW vice anyhow, and new ones cost AU$30 (about US$23) -- and this one has more ''character''.


--GG