ISO 13363:2016 specifies requirements for three types and two classes of hose. The hoses are intended for use in marine-engine wet-exhaust systems (where the exhaust gases are mixed with the discharge of cooling water). It does not apply to outboard motor/personal water craft. The three types are the following: - type 1: a softwall hose, made of oil-resistant material, with a synthetic-fabric reinforcement; - type 2: a hardwall hose, made of oil-resistant material, with a synthetic-fabric reinforcement with a helical wire embedded in it; - type 3: a hose or tube (flexible connector), made of oil-resistant material, with or without a reinforcement or cover, intended for use in short lengths in locations where the connector is protected from mechanical damage. The two classes are the following: - class A: intended for diesel engines; - class B: intended for petrol engines and for diesel engines with a very high exhaust temperature.