The ZXLF-K421+ from Mini Circuits is a Low Pass RF Filter with Frequency DC to 0.42 GHz, Stopband Frequency 900 MHz to 18 GHz, Insertion Loss 1.5 to 3 dB, Rejection 11 to 24 dB, Upper Rejection 11 to 24 dB @900 to 18000 MHz. Tags: Module with Connector, Reflectionless Filter. More details for ZXLF-K421+ can be seen below.