I use dgx valves because at the time they were cheaper than the thermos. I like the thermos because the valve opens very slowly. expecially nice for taking O2 sample. the dgs is like full on in 1/2 turn compared to 2-3 turns on a thermo. You know with a thermo if you valve is only 1/4 open, it will breath hard. The dgx valves I have are tall ones to make it easier to get to valves. Im not as flexable as some are at my age.