Here is the list of manufacturers of Electromagnetic Interference (EMI) filters and/or Radio Frequency Interference (RFI) filters. This list is based on line cards of electronics component manufacturers, and distributors as of 2010.

Abracon Corp (http://www.abracon.com/)
AVX Corp. (http://www.avxcorp.com/)
California Micro Devices (http://www.calmicro.com/)
Coilcraft (http://www.coilcraft.com/)
Com-Power Inc. (http://com-power.com/)
Cooper Electronic Technologies (http://www.cooperet.com/)
EPCOS(http://www.epcos.com/)
Fair-Rite Products Corp. (http://www.fair-rite.com/)
Instec Filters(http://www.instec-filters.com/)
Laird Technologies (http://www.lairdtech.com/)
Magnetic Shield Corp. (http://www.magnetic-shield.com/)
Murata Electronics (http://www.murata.com/)
ON Semiconductor (http://www.onsemi.com/)
Orion Industries Inc. (http://www.orionind.com/)
Qualtek Electronics Corp. (http://www.qualtekusa.com/)
RFI Corporation(http://www.rficorp.com/)
SAE Power Inc. (http://www.saepower.com/)
Sensitron Semiconductor (http://www.sensitron.com/)
Souriau (http://www.souriau.com/)
Spectrum Control Inc. (http://www.spectrumcontrol.com/)
Spira Manufacturing Corp. (http://www.spira-emi.com/)
Stockwell Elastomerics, Inc. (http://www.stockwell.com/)
Surge Control “CCI” (http://www.cci-msc.com/)
TDK (http://www.tdk.com/)
Tusonix Inc. (http://www.tusonix.com/)
Tyco Electronics (http://www.tycoelectronics.com/)
Vanguard (http://www.vanguardproducts.com/)