I believe Dry-Fit is the material used for running and workout shirts. I am interested in the responses too, as a friend wants me to make her granddaughter a tee shirt quilt using her cross country shirts and it will all depend on whether I can get the right interfacing and not melt the fabric, and be able to quilt it. They don't have the money to pay me but the DGD is amazing, so I will do it if I can figure it out.