Flame arrester inlet side

[Sailorsb]

I have the brass Zenith/ Bendix C177-7 flame arrester and removed it for cleaning. Now that it is so clean I can’t tell which side was inlet. It doesn’t look like it matters. Does it?
Also, I don’t have an O-ring on the connector for it to the carburetor, should I install one?
Thanks for the help
Steve B
Cc 35 MkI with Late Model A4

[Dave Neptune]

I believe it is symmetric. If there was a "flow" direction it would be indicated by an arrow.

My O-ring was destroyed when I bought the boat and I ran it without for 34 years. It is probably more efficient with one but not a critical seal.

Dave Neptune