Why do I need point-of-use surge protectors if I have the Primary MB-SPD installed at electric meter?

The primary unit helps protect major appliances including your washer/dryer, stove, refrigerator and water heater. Point-of-use protectors will help protect sensitive electronics from low-level surges that enter through electric, cable and telephone lines. You should have a point-of-use protector for each electronic item you wish to protect. Electronic items include entertainment systems, computers, garage door openers and microwave ovens.