It stands for Sun Protection Factor, which multiplies the SPF number with the time each individual can spend in the sun before turning dark. This is just a guideline and only represents UVB protection.
Do not use this as benchmark for the strength of sunblocks in the market. An SPF100 sunblock may not work as well as a good sunblock with only SPF40.
Our SPF40 and 45 are strong sunblocks and are highly recommended by Dermatologists to their patients.