I have been using e-Gels for my marathons (and long-run training) for over 2 years. I am convinced that e-Gel is the best — for sodium and potassium replacement and for the 150-calorie energy boost. The taste is pretty good, and they digest easily with water just after gulping down an e-Gel pack. Bonking (or cramping) at the 20-mile mark of a marathon due to insufficient energy/electrlyte replacement happens; but, with e-Gel, no bonking or cramping for me.