Each package contains 12 patches that have micro-capsul that contain droplets of lemon eucalyptus and essential oils of citronella. Citronella oil - known as an active mosquito repellent since the middle age - with the strength of the Eucalyptus Citriodora. Each patch has adhesive backing that allows you to adhere to clothing, baby strollers, tables, hats, bags...anywhere you want to keep mosquitos away from. Each patch will give up to 6 hours of protection from mosquitos and other blood thirst bugs. The mosquito patch, when squeezed, releases a pleasant fragrance that repels mosquitoes and other flying insects for hours and hours. Since there is no contact between the essential oils and the skin, the product is totally safe and harmless, even for children. As long as the patches are not squeezed, the life span for an un-open pack is many, many years.