When these oils are blended together, they create a nice scent which is necessary to keep the insects from biting you. The Green Label bottles are dual purpose because it prevents insect bites and also soothes the itch from insect bites. The Yellow Label bottle is an insect repellent only. You will notice another benefit with the Green and Yellow Label, the blended oils are a great skin moisturizer. Each application lasts approximately 6 hours.