Screw on [SMA plug, threaded nut, goes on the outside] - Use this for Antenna Specialist XM-900 series antennas, Terk SIR-6 antenna, Antex Triple Play antenna or radio, or any other antenna or radio with SMA jack. Order a recever end also to make a complete antenna extension except for Antex Triple Play. For Antex Triple Play use two of these to make a complete antenna extension.