The HFE-4-18 from ESJ Technology is a RF High Pass Filter with Frequency 4 to 18 GHz, Insertion Loss 1.5 dB, Rejection 50 dB, Lower Rejection 50 dB @DC to 2.7 GHz, VSWR 2.00:1. Tags: Module with Connectors. More details for HFE-4-18 can be seen below.