Gas Flowmeter, Flowmeter 2-20LPM Meter with Control Valve for Oxygen Air Gas

I'm using this inline towards the breathing end of my hose. I am on very high flow (10-15 LPM) and sometimes I need to bring the level down while I'm asleep or resting because the high setting is putting too much cold air out. This controls the output of two oxygen concentrators hooked together. According to test equipment, this is very accurate and it's rugged, having taken several drops on the floor in stride.It's wise to add rotating fittings so that the hoses don't unscrew the fittings over time.

I have not received the LZQ 7 I use it to measure air flow through a porous refractory.

Doesn't work. . . no clear instructions at all, no hints at troubleshooting... can't get it to even try to work. . .

It's kind of small but actually it works perfect.

Ok