As standard, STORZ couplings come with a vacuum resistant lip seal designed for suction-delivery hoses. The couplings for delivery hoses (with a short hose tail) have a seal that is not resistant to vacuum. Aluminium STORZ couplings are fitted with a standard white nitrile rubber seal (NBR), brass couplings with a black NBR seal and stainless steel couplings with a Viton seal.