Boy, this is a new one....
If you want to run you grill from this adapter, you would connect the hose to the "throw-away cylinder connection...because it has a internal valve (no leak when hose is not connected).
The 1/4" connection is a regular open connection, so it is always connected or always plugged.
I am confused by the picture because the two "main" connections don't look like they are male & female of the same type. This adapter alos converts bewteen the POL (old style) and the quick change (new style). with this really fit on your RV?
This is almost what you want:
inverted flair pigtail
Maybe a propane expert can set us straight...
Dan