What a great product! I know there were other brands that were similar but I went with the trusted ARB brand. This inflator makes it very easy to get accurate air pressure. You don't have to inflate the air and check it with a pressure gauge and twist it back and forth until you get the pressure you want. A simple locking head insert that senses pressure instantly and then pulls the trigger to add more air when needed. Then release the trigger to see what your reading is like. If you need more, press the shutter button again. On the other hand, if you've vented too much, squeeze the trigger to let some air out. You eliminate the rear and fourth part with two different tools. One tool to check everything.