This is a beautiful EAR 660 valve mono compressor.
EAR (Esoteric Audio Research), well known throughout the recording industry, is a super high-end audio manufacturing boutique created by the late Tim De Paravacini.
EAR studio gear doesn't come on the market very often so this is a rare opportunity to get hold of their flaghship compressor, the 660. This unit has just been fully serviced by EAR themselves, and has even had a new faceplate, so it's looking (and sounding) absolutely incredible.