I just received this item yesterday for my 12V Marine Battery on my boat, and I installed it today in less than 5 minutes. I placed this inside the battery box, on top of the battery, and with the included L bracket, and screws, it can sit on top of the battery, and it's held in place by the L bracket (placed in between the battery and the battery box). I didn't have to actually install it onto the battery or box for it to sit without movement. The ring connections (as pictured) were a little large for the screw terminals on my battery, but tightened down properly they still made good, soild, tight contact, and work just fine. I plugged this right into a 50ft extension cord that I run out of my garage, and over to where I park my boat, and it powered right on, and started charging. Other reviewers say that it's loud, but I couldn't hear anything until I put my ear to within 6 inches of the charger. VERY quiet. I also tested the ability to store it in the battery box in the configuration I said about before, and it fits just fine. When I unplug the charger, and lay the power cord on top of the battery/charger, I can close the battery box, and it closes just perfectly with everything stored inside. I recommend this to anyone that doesn't want to have to lug around a battery charger everytime you need to charge your boat battery, this can install permanently near the battery, and all you have to do is run an extension cord to your boat, and plug it in. It's literally like plugging in your boat to charge it, and once your done, you can just tuck all the wiring inside your battery box, and head to the lake. Other reviewers complained about not having a 12 ft power cord, but if you're going to permanently mount this on a vehicle, or boat, or whatever, do you REALLY want to have to wind up, and store 12 ft of extra cable SOMEWHERE on your vehicle, boat, mower, or ATV? That's alot of cable to have to stash somewhere, especially when there really isn't much room on a boat, Mower, or ATV TO stash that much cable. I love it. It works perfectly, great/easy install, and I don't every have to move or reconfigure it if I don't want to. I recommend this to anyone looking for a compact, permanent install trickle charger.