Audiovox XM Antenna Extension Cable SIRIUS XM_TERK XMEXT50 50-FT INDOOR/OUTDOOR AMPLIFIED XM RADIO EXTENSION CABLE. EXTENSION KIT FOR SINGLE INPUT XM RECEIVERS. Satisfaction Ensured. ADDS 50-FT CABLE TO THE EXISTING CABLE LENGTH OF THE ANTENNA FOR XM RADIO SYSTEMS. This item has high quality with reasonable price.