This is a 1-1/2" Triclover (TC) to 1/2" NPT female thread adapter. The flange measures 2" diameter actual. 304 SS.

Not that the thread depth is quite shallow on this unit as it's just a 1/4" thick TC blank cap that is machined (hence low profile). This particular version of this fitting is threaded all the way through the cap with no stop. In some cases your male fitting will protrude out the other side a bit. We do offer a version of this with an end stop elsewhere on this site. In either case, sealing the threads will require use of teflon tape.