It's a typical AT kit, with one minor modification. Instead of the mesh baffle, it incorporates a cardboard piston. Nice flyer on a G-80. I believe AT designed this for L1 certification as it really does nice on a middle H.
Although take my word for it, it will not fly far on an F21. (long story posted elsewhere with pix).
Nice beefy kit though.
I scrapped the piston and went to Kevlar as the piston simply would not fit -> no matter how much I sanded it.
I'll second that - ditch the piston system. it's kinda wobbly flying on G35s so use something larger if you can. H97s work great, or G64 if you are not L1. in single use: G80s if you can find them, etc. even G40s would be better than G35s.