Before you spend those hard earned dollars, do some rescearch first. Your local dealers will try to sell you what they think is best, but this is not always the case. There are many different types of control boxes and as many ways to set up the fence. Here I will give you a few places to start your search and hopefully save you some money and critters. afence.com This sight is good for it will give you difitions of common fence terms. Fence milage guide. Grounding recommendations. How joule ratings reflect perforamce. And a conplete installation guide. zarebasystems.com Many tabs to choose from. Charts & guides is GREAT, for it tells you just which unit can be used for predatiors & which can't. kencove.com Many tabs. And an article on BEAR FENCE. redsnapr.com Again many tabs to help you choose the right fence for your needs. Myself I have a fence that will stop almost any predator, two or four legged. It has over 6 joules & will peg out my tester, which goes to 8000 volts. This is a fence that you don't want to back into or touch by accident. It is a pluse unit, so it will give you a chance to get away from it if you do touch it. Here again I perfer to use equipment that is overpowered. This way if by chance a bear or mountian lion comes by, they just can't walk though it like it isn't there. For anyone thinking of an electric fence needs to know what type of predatior they are dealing with before ever buying a control box. Would someone want to have a fence like mine if they are only dealing with coons, dogs or other small predators? NO, but for those of us that live in bear country it is a must. Hopefully this little bit of information helps save you some money & heart ache.