The Picatinny Arsenal (IPA: /ˈpɪkətɪni/ or /ˌpɪkəˈtɪni/) is an American military research an manufacturing facility located on a 6,400-acre (26 km²) lot in northern New Jersey. The Arsenal is the headquarters of the United States Army Armament Research, Development and Engineering Center. It is known for inventing the ubiquitous Picatinny rail, among other things.