The original 2013 Blackmagic Pocket Cinema Camera squeezed a Super 16-sized sensor and 13 stops of dynamic range into a body the size of a compact - the first truly pocketable raw cinema camera.
It records 1080p ProRes and CinemaDNG RAW to SD cards through an active Micro Four Thirds mount, which takes speed boosters, vintage Super 16 glass and modern MFT lenses alike.
Its significance is the cult it started: the 'OG Pocket' film-like image keeps it in use as a crash cam and B-cam long after its spec sheet aged, and it defined the BMPCC line that followed.
Sellers call it the BMPCC OG or Original to separate it from the 4K/6K generations - listings that say just 'Pocket Cinema Camera' with no resolution are usually this camera. Check battery door, SD write speeds and the easily-scratched screen; batteries (Nikon EN-EL20) are cheap.