These RFI snap-on Chokes are selected for RFI suppression. Install on DC power line to keep ignition noise from your mobile rig and amplifier. Remove RF on cables and wires to your radio station. Isolate RFI on feedline from your station. Two-piece design, snap and lock securely around your cable. Install end to end along rigid cable or loop multiple turns with smaller soft cable. Typical Cable Use RG11/8U. Inside diameter 0.528 inches.