SSM (paid) stealth mode?

I uninstalled my firewall and enabled SSM. Just for the heck of it I went to grc's shield's up test where it passed the trustealth test. I did not have another fireall running and Windows firewall is not enabled. I thought SSM was a basic network firewall and only protected outbound traffic. Or am I missing something here (which is highly likely)?

Also, I checked with procx and process explorer and there were no fw programs running. So is the stealth mode because of SSM?

edit- this was placed in the av section by mistake. sorry.

 

not behind a router

 

by "Basic Network Firewall" I think SSM only controls outgoing connections by programs. It doesnt stealth your computer or provide inbound protection. someone, correct me if im wrong.