I had an older version of the flask with a Velcro holder for my top tube. Used it racing triathlon. It was great. I only used 1 type of gel at the time so I would just squirt more in at the end of a ride to keep it full, rinse the cap off and keep it in the fridge.
Hot water rinse every once in awhile melted out the old stuff. Bought a 2 pack of flasks each year. You can buy gel in bulk to if you are not too picky on flavor.