An antique art deco brass back plate.
I don't see a maker's mark.
It is 8 1/2" long x just under 2 1/2" wide and weighs 3/4 of a pound.
It is missing the raised cup over the hole where knob rests, has some paint remnants and some dings but is overall in good used condition.
A beautiful antique back plate with great art deco styling.