Grayling's piercing jewelry line is made of ASTM F136 implant-grade titanium. ASTM F136 titanium is a highly biocompatible grade of titanium that is used in medical applications like dental implants, hip replacement, and body jewelry! It is great for internal applications because it has minimal risk of allergy and irritation and is non-corrosive. Industry terms like "hypoallergenic" are often thrown around to lure consumers in but there are no Federal standards or definitions that govern the use of these words. Similarly with "surgical steel" there are a few grades of surgical steel that are biocompatible.
Implant grade, as a specific terminology, has objective standards backing it up. Two organizations, ASTM International and The International Organization for Standardization (ISO), develop and reevaluate standards for metals to determine biocompatibility for medical applications.
To learn more about what jewelry is safe for your piercing, we recommend following what the Association of Professional Piercers recommends.