The carbon filter came in today.  I'm glad to report that the top of the GVG fits the 18mm glass joint perfectly. I was planning on testing how the filter works as a chamber, however the bottom joint is too long to fit the bottom of the GVG.  It's very close though.

I'm sure it will fit in a normal 18mm joint. The GVG has a little rim right were the ground portion of the pipe ends, this causes it to stop sliding in.

The filter is a bit longer than I hoped for.  Once I get a bong I'll test it out as a chamber.  Time for more waiting.