My TN friend Kuger... no offense intended, but there were different buckles for suspenders-straps, for garter-straps, and for pants waist-adjustment straps. What those straps have in common is that they were made of cloth/fabric, not leather. So, the buckles for them don't have the typical leather buckle's tongue. A primary difference between each of those types of cloth/fabric straps is their comparative width ...and thus, their buckle's width. Suspenders-straps were wide, usually at least 1.5 inches, so that they wouldn't cut into your shoulder). Pants waist-adjuster straps were comparatively narrow, usually a bit less than 1-inch.
My point is, comparing the size of Jyverb64's sharp-toothed buckle with the US large-cent in the photo, the buckle appears to be the appropriate width for use on suspenders-straps.