Furnish cable operated remote controlled volume dampers in branch ducts located in inaccessible ceilings and where otherwise indicated. Reference architectural drawings for locations of gypsum board, spline etc. ceilings. Dampers are adjustable with standard tools at the ceiling line in a concealed rectangular steel Ceiling Cup RT-CCS or round Ceiling Cup (RT-CCR or RT-CCM) secured to the ceiling or ceiling framing. The Ceiling Cups shall provide a secure, unobtrusive appearance flush with the ceiling surface. Galvanized steel square-shafted damper shall be worm gear actuated via a brass plated rotary cable which is captured at the damper end by a shaft coupling integral to the worm gear assembly. Additional cable retainer supports shall be factory furnished as required by the cable length. Rotary cable shall have a minimum torque service factor of 200% when installed in accordance with
manufacturer furnished instructions. Ceiling Cup, rotary cable, and worm gear shall be furnished as one piece for installation with no linkage adjustment required or miscellaneous small parts. Positive, direct, two-way damper control shall be provided without sleeves, springs, or screw adjustments (that may loosen after ceiling closure). Cable operated dampers shall be Metropolitan Air Technology LLC. Model #RT-200 with RT-WGA worm gear assembly and RT-CCR, RT-CCM, or RT-CCS Ceiling Cups.

US Patent #5,702,298. Canadian Patent #2,185,311.