Corbin Russwin’s history combines high-quality product and innovative
design. That tradition continues with the new Grade 1 DC6000 Series door
closer, designed and engineered with quality features such as captured
valves and a complete range of new arms. The DC6000 series is the
perfect closer for high-use openings or openings that must meet ADA
requirements, such as schools, office buildings, health care facilities, and
retail complexes. The series also meets UL and UL10C positive
pressure requirements for fire openings.
Uses the same mounting bracket as the 100,  and 2800 series.

Older models may have SL72 or MS93 cast on the cylinders.  You may also find Clarksdale, MS cast on the cylinder also.