If by "Milwaukee Ma957" you are talking about just the CO2 regulator, then no. But what I saw when I looked these up, was a "kit" incl. CO2 regulator, solenoid valve, and a bubble counter. I think the bubble counter has a check valve made into it....but I'd just pick up a check valve (inexpensive one) and add it in line.
I don't know if what I found is the same package...but what I saw looked like a JBJ bubble counter. I had one which didn't last a week. The glass cracked, so I don't use it. I'm pretty sure it has a check valve built into it.