Originally Posted by AquaMan
Progressive Industries! Hardwired is best way to go, IMO. Not the cheapest, but offer great protection.
I use their portable unit and am very pleased with it. It seems the main reason many prefer the hard wire is they are worried the portable will be stolen. The portable is designed to take a heavy bicycle cable. I use a cable on mine and don't think anyone could walk off with it without working pretty hard at it.
Heavy Duty Bike Lock and Cable
What I like is if I wanted to I could take it from one unit to another one if I want to. It is also less expensive and very easy to use. Plug it in and let it run through one cycle of tests and if everything is good plug in your trailer. Couldn't be any easier to use. Oh, and has a life time warrantee. Not the cheapest but in my opinion they are the best made units.