You can spend hours or lots of money trying to find every power vampire in your RV. I spent two seasons with my battery always being completely dead when I came back to my RV despite all my attempts to get them all shut off. Then after the second season, my battery would no longer take a charge. My RV dealer suggested a cutoff switch and after some investigation, I went with this one. There are other cheaper and simpler options out there but I wanted something convenient, safe, and durable. This switch really fits the bill nicely. It's very well made and uses high-grade plastics. The switch has a very solid feel, it's easy to know if you are switch on or off. First, there aren't any instructions with this switch, they're mostly here on this page. What you will need to install it is an extra battery cable. There is no polarity with this switch but the manufacturer does suggest installing this switch on the ground (negative) side of the battery as it is safer. This makes sense as any owner's manual or mechanic will tell you to hook up positive first and then negative when installing a battery. When removing one you remove the negative first and then positive, that's in effect what you're doing when you install this switch on the negative side. It took a while but I managed to find a black, 2 gauge battery cable that worked for me: https://amzn.to/2VGcEJg. This switch requires a 3/8" lug and if you are installing this on an RV or boat your battery probably requires a 3/8" lug as well. Keep this in mind as there are also cables with 5/16" lugs (used with motorcycles and other smaller vehicles), either on both or one end. 18" of length was the perfect size for me as it allowed enough slack to go around the box lid easily. The kit comes with four hex head bolts, nuts, and a bottom cover. What's not clearly shown is each of the four side panels is removable so you can pick the best one to remove for your application. Using some trial and error I figured out the proper drill bit size to drill my holes for mounting. I opted to install this switch on the top of my battery box. I started by placing the bare switch (bottom plate removed) on the lid and marking each hole to drill. With what I believe ended up being a 5/16" drill bit I drilled each hole. I then removed the panel opposite the "on" indicator as I wanted the "on" side in front and the cables out the back. I hooked up my extra cable and headed out to the RV. I then made sure the switch was set to "off" and hooked it up to my RVs ground (negative) cable. In the case of my RV this cable is white and you can clearly see it attached to the frame to ground it. With all that done and making sure my switch is still set to "off", I attached the other end of my extra cable to the battery's negative terminal. With the switch off you won't see any sparks when you do this. At this point, I replaced the bottom cover to have some extra weatherproofing as the bolts easily extend well beyond it. I tightened down the bolts to the lid using the standard hex "star" bit that came with my drill/driver set and holding the nut inside the lid with a ratchet. With that done you're ready to re-attach your lid to your battery box and give it a try. Some photos from the manufacturer show a way of installing the switch INSIDE your battery box. There's no template provided for this so you would have to figure out the size of the hole to make for the switch. This probably is more weatherproof and while I do have a Rotozip (you could also use a hole saw drill bit if you figure out the right size) I wasn't sure I had enough room with my battery and thought this was overkill. You could also attach this to the side of the top of the lid with the cables coming out the bottom. With this method though I figured water would be more likely to get in being kicked up from the road or off my truck's tires. So I decided on top with the cables coming out the back was the best option. You could probably use silicone to seal it if you wanted to, I may do that, but that's probably overkill as well. IN USE In use this switch is simple, turn the switch on and there's power to your RV, you also need it on to charge your battery if your RV is hooked up to power or your tow vehicle. I flip it on when I come back to my RV. Once you are going to put your RV in short or long-term storage, switch it off and your days of searching for power vampires or coming back to a dead battery are over. Hopefully, my new battery will last more than two seasons now.