This International Standard gives the requirements for three types of sleeving constructed from polyethylene terephthalate yarns using either braided or knitted construction, with a continuous acrylic based coating and differentiated by their breakdown voltage: high breakdown voltage (sheet 420), medium breakdown voltage (sheet 421) and low breakdown voltage (sheet 422). The sleeving is normally available with internal diameters between 0,5 mm and 25 mm and is normally supplied in the following colours: black, yellow, brown, blue and red. Sizes or colours other than those specifically listed in this standard may be available as custom items. These items shall be considered to comply with this standard if they comply with the property requirements listed in tables 2 and 4. Experience of product performance indicates that sleeving of the types specified in these sheets may be suitable for operation at 130 °C or in some applications at temperatures up to 155 °C.