This is a modern AEA R92 ribbon microphone in with all of its original accouterments. It's designed for close-mic'ing loud sources such as guitar amplifiers, horns, vocals, and drums. The front and back have different tonality, with the front side being crisper and with more presence, and the rear side being darker and mellower.
You can read all about it on the internet because it is still in production.
