SPF (Sun Protection Factor) is a measure of a sunscreen's ability to protect skin from UVB rays. Higher SPF provides greater protection but all skin needs protection from both UVA and UVB rays. SPF indicates how long sunscreen maintains effectiveness before reapplication is needed. A new sunscreen called Derma Essentia SPF 50, PA+++ Sunscreen Gel protects skin from UVB, UVA, IR rays, and urban pollution and is recommended for complete sun protection.