Firestik 2MCKB 4 Ft -122 Cm 2-Meter Base Antenna 5/8 Wave 2 Meter (144-148MHz) base antenna (NOT A CB ANTENNA). 6dBi 5/8 wave design. Solid fiberglass wound with 19 gauge heavy insulated copper wire&#44; approximately 45 long Base threads are 3/8-24. This assembly will mount to the top of any mast up to 1.5 (38mm) in diameter.