Features PREVENT INFLUENCE ON SHORT WAVES: This filter is mainly to filter out FM to prevent its influence on short waves, helps a lot in communication system EFFECT AVIATION FREQUENCIES: This filter also has an effect on aviation frequencies, you can tell if this is the case if you see an image of a BCFM station when you increase the gain that looks like interference from WFM signals on other frequencies COME WITH BIDIRECTIONAL INTERFACE: FM band stop filter is equipped with a bidirectional interface, realize aviation frequency suppression signal interference USEFUL WITH SDR: Broadcast FM band rejection filters are useful in conjunction with the SDR because in some regions the broadcast FM signal is very strong, overloading the SDR, resulting in very poor performance in other frequency bands REJECT 88‑108MHZ SIGNALS: This filter rejects signals between 88‑108MHZ with approximately 50dB or greater attenuation Specification: Item Type: Band Stop Filter Material: ABS, PCB Broadcast FM band stop filters are useful in conjunction with SDRs because in some regions the broadcast FM signal is so strong that it overloads the SDR, resulting in very poor performance in other frequency bands. You can tell if this is the case if you see an image of the BCFM station when you increase the gain that looks like a WFM signal from other frequencies interfering. Package List:1 x Band Stop Filter1 x Bidirectional Interface Note:Pay attention to the correct operation. Package List 1 x Band Stop Filter 1 x Bidirectional Interface