TTW, but they glue to the baffle tube, so not a good surface. Hadn't thought that far ahead when I drilled the holes. I should have indexed the holes to allow a solid surface for the fins to mount to. When I realized what was going to happen, I pulled the glassine off, and applied a layer of glue, creating a double glue surface.
I bought vinyl from Stickershock a couple years ago, but paint has to wait for spring. Winter has arrived in Southeast Texas, it is currently 31, with high of 35 sometime today...