For commercial and institutional projects, this publication contains ratings for TDF and TDC connectors. The data has been standarized on "minimum" thickness rather than "nominal" thickness of sheet metal a major change. The new construction standards contain re-rated rectangular, round, oval, and flexible duct construction for positive or negative pressure up to 10" water gage. Widths go to 120" in gages 26 to 16. Diameter go to 84" in gages 28 to 16. New performance requirements faciliate equivalent ratings for non-illustrated construction. The data has been reorganized for easy use and reference.