I've never done a GST-9, but my understanding is that the jig isn't really "optional" since it also contains the slide rails (not included with the frame). Both are required.Unfortunately it does not come with the jig & stuff. That's 29.99 for the jig with the extra's and $149.99 for the frame. It is worth paying the extra money though in my opinion.
Kind of confusing too since the description clearly states it is a "4-in-1 platfom" and will take a G17 slide... then further down clearly states it "does NOT accept Glock `17 slides".