This upgrade is used to cover the fuselage with .020 PETG plastic. The intention is to protect the belly from landing dammage and make the tail boom stiff for better flight control. lThink of it as coating your model with fiberglass without the work and mess. PETG is the material soda bottls are made with and you know how tuff that material is. Because there was room on the forming platform I thru in a clear canopy as well.