How does our towel block 98% of UVA & UVB sun rays?

The UPF 50+ Sunscreen Towel is made from UPF 50+ fabric that has been throughly tested by independent lab (certifications upon request).  Our towel is not treated with a chemical to achieve this level of protection. Our specially woven fabric is so tightly knit that it blocks 98% of UVA and UVB sun rays.  Additionally, our fabric provides a 4-way stretch without losing it's protection from the sun.