Finned aluminum exhaust flange, clamp or collar. Roughly polished as shown. 44mm internal diameter. Standard size for 850 T, 850 T3, 850 T4, 850 T5, Convert, 1000S, MilleGT, 1000SP, 1000SP II, 1000SP III, Strada, LeMans III, LeMans 1000 all years LeMans IV and LeMans V, California II, California III, California 1100 1994-1997, California EV 1998-2000, California Special (Bassa) 1999-2000. Update for 14121000 and 17121060.
Note on assembly: Do not overtighten these flanges. They are made of cast aluminum and if you overtighten them, they will break. Best practice is to use a lock washer to prevent loosening.