High-pass electronic filter - TC, MC, AC series - TDK Electronics Europe - active / common mode / EMC
All the things you always wanted to know about electronic filters - FEA for All
Low-Pass Electrical Filters, BNC Feedthrough
Amazon.com: Wingman1 Electronic Air Filter Including Year Supply of Replacement Pads - Homeowner Installed- Simply Replace Your Current AC Furnace Air Filter and PLUG IT IN! (16x25x1) : Tools & Home Improvement