GGC Embroidery purchases from a number of reputable vendors.
Here are just a few of the most popular:
Fahrenheit Headwear: http://fahrenheitheadwear.com
Helly Hanson: http://lutzco.net/PDF/helly_hansen_2017.pdf
Otto Caps: https://ottocap.com/
S&S Activewear: https://www.sportswearcollection.com/GGCembroidery
Teamwork Athletic Apparel: https://www.teamworkathletic.com/