4 Inch 193 CFM Inline Fan+Carbon Air Filter+Variable Speed Controller+25-Feet Air Ducting With 2 Clamps Combo 4" 193 CFM Quiet Inline Fan 4 By 16 Inch Carbon Filter Dia 4 Inch By Length 25 Feet Air Ducting With 2 Free Durable Clamps With Free Duct Tape(Width 2-Inch, Length 20-Yard Per Roll) This Combo Bring In The Fresh Air And Remove Heat From The Grow System