This durable two-sided plastic sizing wheel comes with a complete instruction manual for residential and commercial duct sizing procedures. Designed by Hank Rutkowski.

Uses:

• Sizes metal ducts, lined metal ducts, duct board airways, and wire helix flexible ducts
• Converts round shapes to equivalent rectangular shapes
• Correlates available pressure with total effective length and friction rate (Manual D sizing calculations)
• Converts velocity into velocity pressure and vice versa
• Corrects for altitude and temperature