ISO 4081:2016 specifies the requirements for straight or pre-formed rubber hoses and tubing for use in pressurized or unpressurized cooling circuits containing 1,2-ethanediol-based coolants in internal-combustion engines for vehicles with an unladen mass (as defined in ISO 1176) of 3,5 t or less. In addition, this specification may also be applied as a classification system to enable original equipment manufacturers (OEMs) to detail a "line call-out" of tests for specific applications where these are not covered by the main types specified (see example in Annex D). In this case, the hose or tubing would not carry any marking showing this ISO specification number but may detail the OEM's own identification markings as shown on their part drawings.