I have had a Surge Guard since we started RVing in 2009. First one is a 30 amp current one is 50 amp. Still have the 30 amp "just in case". We bought the locking hasp. Since 2009 we have RV'd in many diverse places, some as long as eight straight months. Never had an issue and never plug in without it. The Surge Guards have been out in torrential downpours of 12" in four hours. Never a moment's problems in either operation or theft attempts. With the hasp a thief would need to cut through the Surge Guard's cable to get it off the hasp. Doing that would essentially destroy the device.