Electrically insulating film

The present invention relates to a capacitor film comprising a biaxially oriented polypropylene, a) said polypropylene has a draw ratio of at least 4.0 in the machine direction and at least 4.0 draw ratio in transverse direction of, b) said polypropylene has according IEC60243-part1 (1988), the EB63% breakdown strength of at least 300 kV / mm at a draw ratio 4.0 in the machine direction and transverse direction.