I have been searching for a product to use during my runs for the longest time. I had a friend recommend Tailwind and I blindly tried it. I went all in with the challenge pack and I have not been disappointed! The gels and gus and chews have always wreaked havoc on my stomach. Tailwind does not and is worth every penny. I can power through my long runs and hammer out speed workouts with great energy thanks to tailwind challenge pack!