Sawyer's Controlled Release formula uses a patented Sub Micron Encapsulation process by which the Deet is captured inside a Mycale protein. Each microscopic particle of protein contains chambers which hold the Deet. Over a period of up to 24 hours your skin slowly dissolves the protein particles. As the particles are dissolved, Deet is released from the chambers for evaporation (the function which keeps the bugs away) and your skin is nourished by the dissolved proteins. At any point in time you may simply wash the remaining formula off your skin with soap and water. 4 oz. Bottle Contains 20-Percent DEET.