When shopping for a leather guitar strap (or any other leather product for that matter) it's important to understand the different grades of leather out there:
"100% real leather" is another phrase commonly used. But "100% real leather" tells you 0% about the leather quality or grade. Bonded leather and full grain leather are both 100% real leather, but they are completely different when it comes to quality.
Also, worth mentioning, you may see the above terms combined, such as "genuine full grain leather". Using two terms together just cancels out the meaning of both terms.
The words used to identify leather are, unfortunately, often used incorrectly, sometimes intentionally but usually ignorantly. You can take our word for it that every Anthology Gear leather guitar strap is made from full grain leather. When building the best products, it all begins with the absolute highest-grade materials.