When you're working with iron-on vinyl, you'll need to use transfer tape to help you apply the vinyl to your project. This tape helps hold the vinyl in place while you're applying it, and it also makes it easier to line everything up correctly. Without transfer tape, it can be difficult to get the vinyl in the right spot and keep it there. Most brands of iron-on vinyl come with transfer tape already attached, but if you're using a different brand or if your transfer tape has worn out, you can buy replacement tape from most craft stores. Make sure to choose a transfer tape that's specifically designed for use with iron-on vinyl, as other tapes may not work as well.