Matches HF mobile antennas (ham sticks, screwdrivers, etc.) 10-80 Meters by adding C (capacitance) from the feedpoint to ground to form L-network with antenna. 11 values of switchable capacitance. 30 pF - 2000 pF. Handles 600 Watts. SO-239 connectors. 3½W x 3H x 1¼D inches.