MurrayN. I also use a VIAR 450P. I had been carrying a small 110 volt compressor with me, but wanted something that would operate on 12 volts in case I needed it on the road, or wherever A/C power was not available. Most of the cheap 12 volt units will not handle the 110psi requirement. The VIAR is not the cheapest by a long shot, but it is solidly made and looks like it will last as long as I need it to. I bought mine on Amazon.ca and found it was actually cheaper than ordering from the US due to the BIG difference in our dollar exchange rate. Amazon also ships free, or did at the time of my purchase.