The actuation key CA 12 – produced in self-extinguishing, glass fiber reinforced thermoplastic material – is studied to offer an extra 5 mm working stroke to the safety contacts of the AST series. The internal spring has an actuation force higher than all the internal springs used in the safety contacts of the AST series, and as a result it will start compressing only when the contacts are closed, guaranteeing 5 mm extra stroke of the actuator.