"EUCHNER Safety Switches are used to protect personnel by monitoring and interrupting the safety circuit depending on the position of the machine guard. The locking solenoid holds the guard closed until a stored energy hazard has dissipated. It can also prevent damage to a part in process due to an inadvertent machine shutdown. To meet current worldwide standards, safety interlock components cannot be easily bypassed. These switches have positive opening contacts (in accordance to NFPA 79) and redundancy to guarantee that they fail to a safe state. The TK switch utilizes the same body as the TP switch however has a metal actuating head and locking pin. This unique switch does not require a separate actuator just a separate hole on the door opposite of the actuating pin of the switch."