I have used these Hammer Nutrition gel flasks for my recent races and they are invaluable for numerous reasons. They are very easy to store in a pocket or down the front of your jersey for easy access. They are well marked for quantity - just keep in mind not all gels are the same volume. The two things I like most about these flasks the finger grips (easy to wrap your hand around - especially if you need to hold onto it while running) and the flow through the spout. Depending on gel viscosity, you can get a full dose of gel out in one squeeze - a major bonus for someone with any concerns about race-day fueling.
I am a competitive mountain bike racer and using these flasks is the fastest way to take on nutrition in the form of gels and keep moving forward. When I don't need to take a full 5 servings with me (meaning a completely full flask of gel) I always add water to thin out the mix. This not only makes the fueling time even quicker but also ensures you get all the gel out a lot easier. I have a buddy that adds a little brewed coffee to his flasks to add some caffeine.
I've dropped Gel packets during rides trying to tear open the packet with my teeth and one hand in order to keep one hand on the bars. This eliminates that risk all the while being able to store more fuel in one location. No more need to jam sticky used packets in your pockets.
No brainer. Get a Hammer Gel Flask and buy your gels in bulk. You will save money and you won't come home with a pocket full of sticky trash. Also, the Gel Flask is easier to open than most single serving gel packs.
I can't ride and open gels so I have to stop to do that. Then I have to catch up as my buddies are hard core and will not wait on me.
So the flask works. I don't need to stop.
And I have no litter to deal with.
That's about it. A solution to my problem.