It looks like a regular 6-pin Schlage or aftermarket cylinder. The tailpiece with the hole in it and the other parts are part of the lock actuator. I’d guess it’s for some kind of padlock. The thin disk may be to prevent bypass through the keyway but that isn’t typically an issue with these cylinders as the tailpiece attachment prevents a probe from getting to the mechanism.
The core itself is nothing special. It’s the tailpiece and other hardware that is specific to that lock mechanism. Is it a Schlage brand lock or something else?