Barter Island controlled nine manned stations, four of them being classified as "auxiliary" sites and five "intermediate" stations. The auxiliary stations were similar to the main site at Barter Island; the intermediate sites had less personnel at them. The stations were made up of an AN/FPS-19 search radar, a high power L-Band radar consisting of two identical radar sets feeding a dual (back to back) antenna with a range of about 160 nautical miles. The sites had one 25-man module building for personnel who supported the radar, and an airstrip, although the length and capacity varied greatly, making frequent risky landings necessary at some sites.