This is our triple match, used to give you three choices of base impedance matching on our antennas.. Our High Power antennas come with a single match but sometimes because of mounting/RF grounding/coupling issues one single match is not enough to get a low enough SWR to keep the equipment happy...A must if running a amplifier mobile. It comes with a #5 and #10 Matching "Spud". That will cover all bands on most installs. Includes: Triple Match Box #5 Spud Matching Coil #10 Spud Matching Coil Three Position Switch 20' Control Cable Ferrite Clamp Matching coil covers Install is simple, it clamps to the antenna..You have a antenna side connection and a ground side connection...Coax connection in the center. There are other ways to connect using a T connector. On most installs the center spot(0) is covered, no matching used for 10 to 15 meters..(1) spot uses the #5 spud for 17 to 30 meters and the (2) position uses the #10 spud for 60 to 80 meters. We also have a full matching coil "spud" kit for those hard installs and for those excellent installs.