Deluxe Heavy duty magnet mount. The Diamond DP-SPM is a heavy duty 2.2 lbs., 4 inch diameter magnet mount. It is rated 25-500 MHz. Recommended for antennas under 45 inches. Has a UHF [SO-239] base and 13 foot of low loss 3.5D-2V coax vable to a PL-259 plug.