The primary MB-SPD helps protect major appliances and equipment like your washer/dryer, stove, refrigerator, air conditioner and water heater from surges that come in through the power line. Point-of-use protectors will help protect sensitive electronics from low-level surges and surges that enter through other paths like outdoor circuits, cable TV or telephone lines. We recommended that point-of-use SPDs (plug-in devices) be used to protect products like TVs, DVR/DVD players, computers, printers, modems, low voltage lighting, microwave ovens, garage door openers, and security and irrigation systems. Other costly and sensitive products like pool or well pumps, elevators, and golf cart chargers should have special SPDs for the protection. You should have a point-of-use protector for each electronic item for the best protection.