Without locking of actuating key. Metal case key-operated switches for use on machines with low inertia and operating in normal conditions (no vibration or shock and guard mounted vertically, without risk of rebound on closing), thus helping to eliminate unintentional opening of the guard.
With locking of actuating key and manual unlocking. Metal case key-operated switches for use on heavy machines with low inertia and operating in arduous conditions (shock or vibration), whereby the guard could open unintentionally.
A key-operated lock or a pushbutton enables positive locking of the guard and its subsequent unlocking.