Do not install warning
Inside the package is a warning: "DO NOT install this device if there is not at least 30 feet (10 meters) or more of wire between the electrical outlet and electrical service panel." A phone call to customer support explained that 30 feet is required else the power surge protection won't have sufficient time to react. Should a surge affect a device and the device isn't more than 30 feet from the house electrical box, I was told that the warranty would be void. The 600 joules rating is very low protection in any event. Buy this for the convenient outlets, on sale (I paid $10). Look elsewhere for surge protection.
I guess I would agree, but I had mine connected above the electrical panel and we got a surge and everything is still fine. I think it must mean the length of the wire from the box to the surge protector should be no less than 30 feet, which isn't hard because there is at least 10 feet between the box and my first outlet in the garage. Either way, I'll agree, get a better protection device if you really need the protection, this is more of a outlet expander.