Leviton #8052-999 unglazed porcelain fixture socket. This is single circuit, keyless, medium base with 24" wire leads, rated 660W 250V. Bottom has inset and mounting screw for a mounting bracket up to 0.3625" wide so that you can use it with your existing mounting bracket. Most brackets are just under 11/32" wide so this will fit on the standard size just fine.
