This is for inflating car tires?
I use a 5 gallon air tank, the original tire inflator hose replaced with a ~2 foot hose with a typical air tool quick-connect on the end. I fill it off my compressor, but one could just as easily fill it with a small plug-in air pump... It would take longer, that's all.
The quick connect lets me attach air tools such as an impact gun to take off a wheel's worth of lugnuts, or an inflator. For tires, I use a nice
Harbor Freight inflator, the long tire chuck thing replaced with one of the
spring clip chucks that Snax mentioned.
The tank is a bit bulky to carry around in the car, so I guess that tosses it to the back of the pack, option-wise, but I thought I would throw it out there just the same.