This part of IEC 60371 gives requirements for electrical insulating materials made by combining mica paper with glass fabric and bonding them together with a small amount of epoxy resin. The material is supplied in a flexible state and is designed for use in conjunction with vacuum pressure impregnation (VPI) with compatible impregnates. The final cured properties will be primarily dependent on the VPI resin used. Two bond contents are specified: – low bond with a resin content of (8 ± 3) %; – medium bond with a resin content of (16 ± 3) %. Materials which conform to this specification meet established levels of performance. However, the selection of a material by a user for a specific application should be based on the actual requirements necessary for adequate performance in that application and not based on this specification alone.