How do I know if I have Heat Transfer Vinyl?

One strong indicator that vinyl is heat transfer and not adhesive backed is that heat transfer vinyl does not have a paper backing and adhesive backed vinyl does. Heat transfer vinyl has a plastic backing that is almost always see through. They make it this way because when you cut heat transfer vinyl you cut it mirrored and flip it over before pressing, so you need to be able to see through the backing in order to properly place it on your garment before pressing HTV.