FREE: Mystery Tool #2 - Solved!!

Another of my late father's treasuresfromthetoolchest: Okay, so although I label this a Mystery Tool, I do realize that it's a clamp. Duh. But what kind of clamp?...I mean, what is it intended to clamp? It's design seems to permit something to be inserted through it's centre and then squeezed tight by two opposing right angled brackets (best shown on photo#4). There is, however, two intruding clamp-pieces that forbid the insertion of material to bear against the right-angled clamping surfaces - a frustrating predicament indeed! Not sure if my photographic efforts adequately present the quandary. One of the photos depicts the part no., I think, STANLEY C.575 (not sure about the decimal). I've researched to no avail (Luddite that I am). Can't wait for the Internet's wide group of intelligent and playful characters to provide their insight and/or humorous suggestions for the use or abuse of this little item. And, of course, free to the most desiring of respondees. Well, this has certainly generated a lot of traffic - 45 responses, so far (they seem to come in bursts!). Oh my, sorry to have wasted so many peoples' time. Yes, the Stanley tool number that I (mis)quoted allowed many eager beavers to track down the proper name of this tool: Auger Bit Depth Stop Gauge (ABDSG). Indeed, when several respondees talked about a "brace", I remembered another old tool dearoldDad bequeathed to me: see the two new shots of the ABDSG installed and three bored holes as a product. I'd like to thank the many respondees, particularly those with some colourful ideas about the use of this gauge: "receptacle for knife handles of specific type" while sharpening, I guess; brake line clamp (!); one half of an old window lock (this gets the prize for most colourful, and I do agree that it has that look about it); but the main prize goes to BC who figured that this Stanley device is meant for clamping a Japanese Katana blade while sharpening. BC must have a fine collection of these Asian knives? Thanks to all who responded. Oh, and sorry to disappoint: now that I know what it's used for, I'm gonna keep it! I am pleased to know, however, that when I decide to bequeath my own collection of tools, there will be plenty of interest! Best to all.