Round Charcoal Filter Type A NT AIR For a ductless (recirculating), use two round charcoal filters "Type A" that attach to the motor to help remove unwanted kitchen smells, this is an optional extra and the chimney section with the pre-cut vent must be used when outside ventilation is not possible. Compatible with NT AIR, models: STD-100, CH-105, CH-106, CHR-114, CHR-115, CHR-117, KA-140. Two round charcol filters "Type A" for each Range Hood.