The Zenith 133.8 watch movement, which is equivalent to the Longines 501, is an automatic movement with a sweep second hand and a date function that can be set by changing the time to 19:30-24h. This movement line was originally designed by Record and later adopted by Longines after their acquisition of Record. It is unclear if the later variants with 21600A/h were also available as Record calibres. The movement was introduced in 1955 and has been in use since then.