FSD-RD is a series of BAS-CVS UL/ULC classified combination fire & smoke dampers manufactured with “True Round” type blades. These dampers have been investigated for both a fire protection rating of 1-1/2-hour or 3-hour (UL555) and at minimum 2000 feet per minute at 4 in. w.g. of static pressure for a leakage rating as defined under Class I or Class II (UL555S).