Any surge protective device that you consider must be listed UL 1449 3rd Edition. All manufacturers UL listings are available for review on the UL website. Be careful not to confuse SPD listed products with secondary surge arrestors such as lightning arrestors. Secondary surge arrestors have a clamping voltage much too high to protect sensitive electronics. When comparing surge protectors it is important to consider both the surge current capacity and clamping voltage to determine the performance of the surge protector.