Graphic 1877 DF & L Ventilator Grate in Original Paint knot 3 3/8" widest

3 3/8"  widest

And then those teeth

Largest (including two planes together at bottom right) measures 6 1/2" x 4 5/8"

and made by the US Embossing Company I believe with letters (on four sides

Graphic 1877 DF & L Ventilator Grate in Original Paint knot 3 3/8" widestJust a great looking thing. I've had one other of these and will always grab them when I see them because they're just so graphically satisfying and pretty fun to operate, too. Produced by DF & L with an 1887 patent date; I haven't found out most anything about the company, but believe they were New England based as that's where these seem to surface. The center dial on this one turns very smoothly to open or close it, and the original baby blue