• Ducts, Inc.

• DuraLast Products Corporation

• Duro Dyne Canada

• Dust Free

• Dustvent

• Dwyer Instruments

• E-Z Filter Base Mfg.

• ECO Corp.

• Earl Swensson Assoc., Inc. (ESa)

• Ecco Heating Products Ltd.

• Ellis & Watts

• Engwald Corp.

• Envirco Corp.

• Environmental Corrections

• Environmental Elements Corp.

• Exhausto

• Fab-Tech Incorporated

• Fan America Inc.

• Fiber-Tech Engineering, Inc.

• Fiberlene Filters

• Filtration & Media Group Inc.

• Fisher Hamilton

• Flanders Corporation

• Freudenberg Nonwovens

• Friedrich Air Conditioning Co.

• Fryston Canada Inc.