Rielda has established itself as one of the most dynamic and expanding companies in the world of security systems. Its international success has been reached through the development of inno- vative cylindrical locks which allow for an unprecedented key control management:the mechanically Re-Programmable cylindrical locks. Rielda's mechanically re programmable cylindrical locks allow the user to change the key in use with a completely different one without changing the cylinder. Half a turn of the programming key is all that is necessary to change the combination and make the previous key useless. It is unne- cessary to remove the cylinder from the support. In so doing it is easy to make lost keys, non returned keys, unauthorized copies or keys that have ended in the wrong hands completely use- less.