The Ronda 1218-21 watch movement is a detached manual wind movement that was produced with different oscillation frequencies, including 18000 and 21600 A/h. While the 558 variant is not documented in movement catalogs, only samples with 21600 A/h have been discovered. The reason behind the signature change from HPP to HJP on these samples remains unknown. The differences between the 450 and 460 variations of this movement are not specified. With regard to its functions, the Ronda 1218-21 movement features automatic winding and a sweep second function. This movement was primarily used during the approximate period of 1970.