Guard locking mechanism HST® TZ2 features 2 locks and is used in applications with accessible area. The operator takes the second, personal key into the danger zone. This personal key can also be used for other functions (e.g. teach mode), or the operator can carry the personal key along as described previously. Before the personal key visible in the picture can be removed, a matching key must first be inserted and turned in the empty lock part. The personal key can now be removed and the previously inserted key is trapped.