The Sidewinder was quickly reverse engineered as the K-13 (also called R-3 or Object 300) and entered limited service only two years later in 1960. This was followed by the improved K-13A(R-3S, Object 310), which entered service in 1962. The R-3S was the first version to enter widespread production, in spite of a very long seeker settling time on the order of 22 seconds (as opposed to 11 for the original).[5][dead link]