MasterCube 688 joules surge supressor Master Cube Surge Protector Youre busy filling your suitcase with the necessary items for a business trip. Pants, shirt, jacket, laptop...surge protector? With a Belkin MasterCube you can protect your laptop from over voltages -- plus, its compact, so it fits virtually anywhere. The Belkin MasterCube protects one electronic device and one phone line from over voltages. Perfect for use with laptops on business or personal trips. 1 Outlet, 688J, Telephone, 10K Connected Equipment Lifetime Warranty.