Here's some tips that might help you install this in a 2012, 2013 Ford Focus. You'll need a 7 mm socket and an extension for your ratchet. There's four 7 mm screws that hold down the top of the airbox cover, and you'll need the extension for two of them.Once you get the screws loose you might have to jiggle the airbox cover to get it off. With the stock air filter, try lifting it up from the back before you try and pull it out, because the back cover of the filter fits in a groove at the bottom half of the airbox.Before putting this new filter in, try slipping the top air box cover on it so you can see how the end cap of the filter slips into the groove. You've got to line it up perfectly and get it in the groove or you won't be able to line up your screws when you put it back together.When you put in this new filter stick the mouth part over the inlet pipe, reach down with your fingers and grab the bottom of the filter end cap, lift it slightly and push/slip it into the bottom groove of the airbox. Make sure the filter is properly inside that bottom groove. Then when you put the top half of the airbox cover on, slip the end cap of the filter into the groove first then set the cover down flat. All your screw holes should line up if you got that end cap properly in the grooves, top and bottom.I had trouble lining everything up at first till I figured out how to get it properly in the grooves. It fits perfectly and was easy to install. It just took me a while to figure out the groove thing. But now that you know and if you focus on getting it in the grooves it will line up perfectly for you.I haven't driven the car yet, but it starts up fine, and idling and revving the engine in my parking stall it sounds smoother. Idle is rock solid stable and it seems more responsive to throttle. I love K&N filters so I'm kinda biased, they go in all my cars. But I really can tell the difference. It's great. Take your time installing it and you'll love it.

Filter looks fine, however the Canon lens cap for the camcorder did not fit very well on the filter, so I will have to get another lens cap.

Great value. Pictures look good with filter. Provides camera lens protection. Lens cap fit with filter on.

Stupidly opened my camera bag while it was upright and my camera came tumbling out onto the floor, lens first with the cap on. The cap and filter took the majority of the damage and it shattered into quite a lot of small pieces which was a bit of a nightmare to clean up and the filter ring was bent so is now stuck on there, but I dread to think what would have happened to my lens had it not been there. Also saved my front element from a couple of water splashes and countless scratches. A must-have for anyone who wants to protect their kit.

The threading of the filter for the lens cap or threaded hood is not 82mm. I just purchased an 82mm lens cap and hood only to find out it is too large. Looks more like it needs to be a 73mm to 75mm thread. The 72mm thread for my lens is correct, however, and works well.Update 11/4/2020: Ordered a 77mm to 82mm step up ring. The ring fits and means that this is a 77mm thread and not an 82mm thread for the cap and hood. If you buy this filter, you will need a hood and lens cap for a 77mm thread.

I set this on top of my monitor - which is great. Also comes with a little tripod if that helps you. I particularly like the little lens cap that it comes with - I use it for a work computer and I like that I can physically cover it.

I originally did not buy extra magnetic caps but really started to like them assuming you always take your filter off when storing. With a filter on as others have said it can be difficult to just take the cap off, but I rarely found this to be an issue.I had been just leaving the magnetic cap on the lens I was shooting with and moving my clip caps after switching lens. When hiking with a camera I found it really nice to take on and off for quick shots. Maybe it's less useful if you are storing your camera in your bag.Protection wise, attachment on these is great. I fell hiking and the cap stayed secure and prevented lens damage so for this reason alone I'm buying extra. I have no doubt a clip on cap would have dislodged. See picture for detail this fall shredded my hands and knees and minimal chipping on the lens cap, no damage to the lens.

It's a UV filter. Increases glare at night, but keeps dust out of my lens when I take the cap off. Decent tradeoff; I just unscrew it off for long night photos. If you take a lot of night photography you should stay away, but for all other cases it's not a bad buy.