These ferrite chokes are required on each cable of L-RX201 RFID Reader Installations where unshielded CAT3 or CAT5 cable is used. Installing the chokes on the cable reduces the RF Signal that is induced into the wiring when tags are nearby, which otherwise would be detected as reflected signal. The Ferrite chokes provide stabilty and reduce erroneous signals on the ReaderNet RFID Network. Sold in sets of two.