I recently experienced a flat tire, from a slow leak, while my family was at a local waterpark. I have roadside coverage, BUT my friend had a battery operated inflator and easily pumped my tire up, allowing me to drive to a garage.I knew instantly I needed one of those in my car going forward! I already owned several Milwaukee tools and batteries, so it only made sense to purchase a Milwaukee tire inflator. I'm both old and handicapped, but I can easily attach this inflator to my tires, set the desired pressure and count on this inflator running to the set point and automatically shutting off. I love not having to unroll compressor hoses, waiting on my compressor to reach pressure or having to test my tires with a gauge. It's fairly small, easy to store in your car and definitely easy to operate. However, it is not super fast inflating tires and tends to run hot for jobs taking more than 10 or 15 minutes. The M18 version is much larger, better capable of heat dissipation, inflates much faster and more heavy duty. It just depends upon your needs and how often you plan to use the inflator on which to choose. I opted for the M12 for its size and easy portability. In either case, you can't go wrong with Milwaukee!