Biplane,
The instructions for the A-26 say's you can remove wrinkles in the covering with a heat gun so I guess it's a heat shrink material.
The quality of the plane is "OK" considering it's the only ARF of it's kind on the market. I'll run epoxy down all joints to reinforce, make a "gun nose" for it, install Spring-air's and OS-52 4/strokes.
I have the silver one. Be sure to check it out really well for shipping damage before you buy if you can, they are not packed well!