Furnish and install Anemostat model (API-S)(API-F) plenum-slot high performance supply diffusers for the lay-in T-bar system as shown on plans.  Diffusers shall consist of 1 or 2 slots, with 1/2", 3/4", or 1" slot widths.  Diffuser lengths shall be nominal 24", 36", 48" or 60" as shown. 

Diffusers shall be constructed from minimum 24 gauge zinc coated steel.  The exposed face surfaces and pattern controllers shall be painted flat black.  Center tees shall be Anemostat Arctic White.

API-S
All movable air control components shall be extruded aluminum -steel and plastic control components are not acceptable.  Inverted tee members and pattern control components shall be secured to steel cross members with heavy-duty springs. These components shall be removable, without tools. The aluminum extruded flow control vanes shall be independently adjustable within each slot to control air volume and pattern (direction) for 
vertical or horizontal directions. Diffuser lengths greater than 36" shall include multiple piece flow control vanes. The physical appearance of the face of supply diffusers shall not change regardless of these adjustments.

API-F
The aluminum extruded flow control vanes shall be independently adjustable within each slot to control air volume and pattern (direction) for vertical or horizontal directions. Diffuser lengths greater than 24" shall include multiple piece flow control vanes.

Model API Optional Accessories
Provide field mounted inlet balancing dampers as scheduled. Plenums shall be insulated with (1/2" internal insulation) (1/2" external foil-faced insulation) (1/2" internal foil-faced insulation) (3/8" internal fiber-free foam insulation).  Diffusers with internal insulation shall be formed with an offset such that the insulation does not impede air flow into the neck of the diffuser. Straight sided diffusers will not be accepted with internal insulation.