The most common system used by fire departments in German-speaking countries is the Storz coupling. That is why the Storz coupling system is also known colloquially as the fire department coupling. The Storz couplings are not screwed together, but connected according to the principle of a bayonet lock. The claws (technically: lugs) engage in corresponding contours of the counter-coupling and are connected or disconnected there by a 120° rotation of the two half-couplings. The distance between the lugs also determines which couplings can be combined with each other.
