Spf stands for sun protection factor. Solar lights versatile spf 290as uv transmittance sunscreen protection factor analyzer is an integrated turnkey uv spectrophotometer designed and optimized for the determination of spf values on a variety of sunscreen and cosmetic products as well as materials testing. Spf Chart Not all of these sunscreens will work for your skin but the above chart is a good place to start when searching for the sunscreen that will both feel great and offer maximum uv protection.