There are a number of tools I have for my old Mercedes that I know I will use maybe once every year or longer. But when you need them you need them.Tools such as one to pull the instrument cluster.I'll check my tires at least once a month. That should be standard procedure for everyone. Came across one last week where it was down to 18 pounds and took it in to have the leak fixedWhen service stations did car repair work they all had nice big air compressors for their air tools and of course hoses to fill tires.Remember when every island by the gas pumps had a hose for water for the coolant and a air hose for the tires?Those days are long gone, with the disappearance of repair shops in service stations. If a self-serve station has an air compressor at all it's some dinky little thing in the back and most want $1.50 for three minutes to fill your tires.And that's if the thing works. And of course I spent a number of years running around the car trying to fill each tire before the time went outAnyway a friend told me about this little portable Dewalt air compressor.It arrived yesterday and I spent today just filling the spare tires of my cars.That's some thing that virtually everybody ignores, including me. And of course the worst time to find out it's low on air is when you need it out in the middle of nowhere.One of them that hadn't been checked since new, 11 years, was down to 10 pounds when it should've had 61 pounds . And of course normally when you find that out it's when you need itOne thing I advise when you're getting this get the bigger battery. I got the middle one at 4 A/h.The only thing that surprised me a bit is after filling these three spares today - the usage light on the battery was down to two from the three. so I suspect if you'd had the standard battery I pretty much would've used it all.The other thing that surprised me is how accurate the built-in pressure governor is. Set it to 33 pounds and it automatically fills it to 33 pounds and then stops. I verified it with my hand-held digital tire pressure gauge.Another nice feature that I had to figure out? Every hose I've ever used do you have to keep it pressed into the Schrader valve. This one just screws in and you just leave it alone while the compressor does its thing. It's a nice thought-out feature.So my summary is that this is a worthwhile investment that you will probably use at least every monthYou can't even depend on the car's tire pressure monitoring system to give you an accurate reading. The one on my 2011 Mercedes is 5 pounds optimistic. I suppose what it is still good for is detecting a massive leak.And the federal government mandated these for newer cars because people don't check their tire pressure.And why is this important? A low pressure tire is in danger of a blowout with the added heat not to mention a degradation in handling.So I am glad that I got this finally.I'll even take it on long trips because looking at that little dinky spare tire in my 2011 Mercedes and the hassle of changing it to a spare it would be nice to have a pump just to pump it up with air and get you do a tire shopThis is a tool that I know I will use on a regular basis.Edit 12-5-22 as I am typing this I'm sitting in an Elko Nevada hotel room. I had taken the 2011 on a 2000 mile trip to Minneapolis. And on the way back I had a tire issueAs it turns out I really did use the air compressor. The other day in Wendover Utah I came out the next morning and the rear tire was completely flat. Now that alone would've taken out a good part of the day being it was in a motel parking lot. call AAA wait a number of hours-& since the things completely flat they probably have it towed somewhere unless they have air compressors. incidentally the spare is this little donut thing that I wouldn't drive the remaining 500 miles on. Anyway out came the Dewalt and in about three or four minutes the completely flat tire was full and used another bar from the batterySo why am I in Elko? I wanted to get the flat fixed and then trying to take it off the rim the machine tore the sidewall and of course there was not another Perelli tire in my size in Elko Nevada so I was having to wait until Monday for one to be deliveredAnyway on a trip I am not going to leave this