Don't know that it is, as I haven't used one with a trigger, although clearly the knob allows you to let go, as it fills at a controlled rate, thereby not freezing your fingers (plus the one I mentioned has a leather tube to slip over the CO2 canister to protect your hand from the cold). I was comparing the knob design to those where you press the inflator over the valve stem to release the CO2. I found that approach more prone to failure, especially if you neglect to open the valve (Doh!) It's either open or closed, and by the time you realize the valve is closed, the canister 'ist kaput'. If you have merely cracked open the knob, and realize you didn't open the valve, that's a 'recoverable incident'. Of course, due to my feeble mind, I now always remove the valve stem cover and open the valve before I store a tube in my saddle bag. That way it's ready to go, saving time and preventing any chance of my trying to inflate the tire with the valve closed.