Critical Load Surge Protector Taking compact protectors to the next level, MCG’s PT Seires is the most advanced non-modular surge protector that money can buy. Within it’s compact 10×10” enclosure, there are up to 20 high-energy, thermally protected varistors packed inside. These high performance varistors are typically only found in much higher priced protectors. The PT Series guards small to medium sized electrical panels. Delta models also available, contact the factory for more information.