check valve help

[JHZR2]

Hi,

Ordered the check valve to replace the green one on the top of the plastic thing (???) next to the alda.
Mercedesshop doesnt offer a green one. I ordered one of each color (black blue, black white) figuring mabe one would look substantially different, and if worse comes to worse, I could just use T&A.

However:

I don't know the directionality of the check valve, there is no arrow on it. I used the arrow on the check valve on the brake booster line (which I also replaced), to determine what side went towards the vacuum pump in the overall setup, and copied that, but I cannot be sure that this is correct.

Can anyone give me some info as to how these check valves are to be oriented?
Thanks

JMH