The actuation key CA 11 – produced in self-extinguishing, glass fiber reinforced thermoplastic material – is studied to offer an extra 3 mm working stroke to the safety contacts of series AST and AS 3. The internal spring has an actuation force higher than all the internal springs used in the safety contacts of series AST and AS 3, and as a result it will start compressing only when the contacts are closed, guaranteeing 3 mm extra stroke of the actuator.