Specifies the diameters of the flexible metal hoses in accordance with ISO 7657 and tested in accordance with ISO 7658 without external coating (as defined in ISO 7369:1983, 4.1.10), used under low pressure, with permissible leakage, at temperatures between - 20 °C and a maximum of 230 °C. The packing should not be asbestos. Suitable materials include cotton, fibre-glass, nylon, Kevlar, polyamide, polyester, etc.