Get your own Rad Rat iron-on patch! Every side of the triangle is 3 inches, making it the perfect size for a hat, a bag, jacket, or anything else you can think of.
The backing of the patch is like hot glue. Iron it through the material from the back for best results.
Chip, the maker of the patches, recommends Shoe Goo for applying it to hats:
Apply/ spread a thin, but total coverage layer of shoe goo to the inside border edge of the patch and stick it to the hat where you want it. It’s really as simple as that. That’s how I apply patches to hats and it works very well. Should take about 60 seconds to cure enough that you can just set it aside. During that 60 seconds, squeeze the patch from center to the edge. and keep applying pressure all around, especially at the tips.