Durozone FSSO1020 Spring return fixed size damper.Item #37098 Duct height 10" duct width 20" 24V motor normally open, motor on 10" side, single blade damper. Free freight on this item in the continental U.S.(UPS Ground) Items are new and unused in original box. Please  call (952) 884-8266 with questions call (612) 518-6683 After 5:00 and on weekends. I ship nationwide.  Minnesota residents will be charged sales tax.