Deet Spray comes in many strengths
The higher the percentage of deet, the stronger the mix and the longer the protection provided by the spray.
100% Deet is the strongest, this is maximum strength and works best in toughest environments (jungles, safaris, high malaria-risk areas).
50% and 55% Deet is for people with sensitive skin in high risk areas or people wanting ultimate protection in Europe.
30% Deet works great in England, Europe & the USA but if you're traveling to Africa or other high risk areas upgrade to one of the stronger strengths.