Command Module Environmental Control System (ECS) fan. Fan measures 3.75 x 4 x 4 and has a four-section metal blade at the front. An Airsearch Manufacturing Co. label is affixed to the housing and reads, “Fan Vane Axial…Serial: 36-171, Order NAS 9-150.” Casing also bears several inspector’s stamps, one dated October 10, 1968. In fine condition. These fans were used to regulate atmospheric circulation, temperature, and aid with filtration of airborne contaminates. RR Auction COA.