PG-F and PG-H are made of high-strength glass yarns laid parallel and bonded with polyester resin. PG-F is used for Class F insulation and PG-H for Class H insulation. They are supplied in stage B and turn into insulating material with high tensile strength and low elongation after hot hardening. They are used to replace the steel clamps of the DC coil and the dry and resin moulded transformer clamps. PG tapes should be stored below 10 °C and returned to room temperature before use. The duration is about 6 months at 20°C and 12 months at 10°C.