Fixed pattern slot diffusers

F-Series fixed pattern plenum slot diffusers for T-bar lay-in or hard ceiling applications.

Standard Construction

  • Up to 4 slots wide
  • Up to 60" long in a single section
  • Supply and return units
  • For use in ceiling grids with 15/16" or 9/16" Tees, or in hard ceilings


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F Series Slot Diffuser – standard T-bar or hard ceiling
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F Series Slot Diffuser – 9/16" Fineline® T-bar ceiling
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Surface Mounting Frame
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KEES, Inc.
KEES, Inc.

Options & Accessories

  • Internal duct liner insulation
  • Internal or external foil faced insulation
  • Elastomeric thermal insulation
  • Inlet damper with manual quadrant lock
  • Two slot units can be configured with or without a center Tee
  • Surface mounting frame for use in hard ceilings
  • Cross notch in plenum for cross Tee
  • Top inlet collar
  • Multiple collars
  • Non-standard collars
  • Non-standard unit heights


  • 24-gauge galvannealed steel plenum
  • Extruded aluminum Tees and surface mounting frames
  • ½" fiberglass duct liner internal insulation


  • Off-white face and interior
  • Off-white Tees