Broadcast FM Band Stop Filter (88-108 MHz FM Trap) By RTL-SDR Blog Features: This filter suppresses signals between 88-108MHZ And has an attenuation of about 50dB or greater Broadcast FM band reject filters are useful for use with SDRs Because in some areas the broadcast FM signal is very strong,causing the SDR to be overloaded Resulting in very poor performance in other bands If the image of a BCFM station is seen when the gain is increased Interference that looks like a WFM signal at other frequencies Then you can determine if this is the case Specification: 1.The main purpose of this filter is to filter out FM and prevent it from affecting shortwave 2.This filter has a deeper pit which also affects the air frequency 3.Weight:25g 4.Dimensions:27.5mm*25.5mm Package Includes: 1*Filter Note: Includes the above packaged products only Specifications are manually tested and are for reference only Please refer to the actual situation,thank you