I have been using them for many years and they have helped me a lot - Hammer Heed for preventing cramping and keeping hydrated and the gels for energy. I use mostly for endurance mountain biking and riding in heat on the road. They seem to be gut friendly for me and I am susceptible to heartburn etc. They are also a very good company for sponsoring some of the smaller races and rides out there - very much an advocate for the cycling community. The only product they have that I do not like is the recovery drink mix - just taste bad in my opinion otherwise everything else taste and works as it should.