The SSD120-(XX)N and SSD120-(XX)NE are all solid-state Altitude Encoders. These devices provide a rugged and reliable means of measuring air pressure and converting this measurement into the ICAO parallel data as set forth in the International Standard for Pressure Altitude Transmission. In accordance with U.S. National Standards for Common System Component Characteristics for the I.F.F. Mark X (SIF)/Air Traffic Control Radar Beacon System SIF/ATCRBS.