Safemaster STS is a modular safety switch and key transfer system made of long lasting stainless steel. It is designed by Dold to be used on guard systems with gates and covers and combines the advantages of a safety switch, solenoid lock and key transfer in one system. One of the most important advantages is the protection against being locked in by means of a safety key. It allows electrical monitoring of the main access gates. Other seldom used doors, e.g. for maintenance are mechanically monitored by key transfer and therefore need no wiring.