re: Plumber baws: diy double vanity question

That's a 2" PVC Double Wye with a cleanout in the middle hub. The black ring is sa 2" x 1&1/2" bushing...your outlet pipe is probably 1&1/2" so you won't need the bushing. Try a plumbing supply store like Coburn's or Southern Pipe.

Looking at your picture you will have to swing your p traps against the wall and possibly use an offset fitting like a 45* or 22* to get the drain pipe back as far as possible.