The 'SBT1' twin fins stem from Shyama spending time with Ryan Burch and riding his pickle fork design. The fins have been created to give a dynamic relationship between drive and response. The template sits in between a keel and a standard upright template, let's call it a Medium tweel.
“This reduces the erratic nature of the upright templates but gives you a more dynamic response than a directional keel fin. Because of this, I recommend that a stabilizer fin is not needed.” - Shyama