Data Sheets: 1NI-C 1B 1M

Designed for efficient installation and engineered to precise standards, our flexible duct sets the standard in quality and dependability. Unique to others in the industry, we manufacture flexible ductwork without the use of glues or adhesives. The mechanical-locked inner core maintains its shape at all 90° bends and offsets, thus eliminating the need for extra reinforcement.

This manufacturing process produces a flexible duct with the highest performance credentials of any flexible duct. The Flexmaster U.S.A.® 20 year warranty is unsurpassed in the HVAC ductwork industry.

Type 1NI Flexible DuctType 1B Flexible DuctType 1M Flexible Duct


  • Acoustical testing was performed in accordance with ASTM E477
    and ADC Test Code FD 72-RI by ETL.
  • Insertion loss values are for flow velocities less than 2,500 fpm.
  • The 63 Hz IL values were laboratory measured, but were not
    published due to lack of  acoustical value.

Universal Characteristics

  • ETL Class 1 Air Duct
  • Flame/Smoke: 25/50
  • Operating Temperature
    Range:-20oF to + 250oF
  • Rated Velocity: 5500 F.P.M.
  • Available Thermal Conductance
    (R-factor): R4.2, R6 or R8
  • Standard Length: 25 Ft.
  • Vapor Barrier Permeance: 
    Black Polyethylene (B) -
    .10 Perm A.S.T.M., E96, Procedure A
    Silver Mylar (M) -
    .05 Perm A.S.T.M., E96, Procedure A
  • Connector Rated: Limited to 14 Foot Runs
  • 20 Year Warranty - Except Type 9 (5 Years)

Robust Mechanical Lock Construction

ETL Class 1 Rated

UL 181 vs. ETL

Nationally Recognized Test Laboratories: