Amphipod Hydraform Jett-Lite Thermal 12 ounce

I originally bought the 20 ounce back in 2011 as I was preparing for my first NYC marathon. I loved it!!! Eventually I had to replace it but I wanted something smaller and just went with another brand, cheaper. However, after moving to Puerto Rico, I needed to carry water on any runs over 4 miles but didn't want the hassle of it slipping out of my hand. I went back to my favorite Amphipod but this time went with the 12 ounce. It's perfect!!! It hardly feels like I have anything in my hand and holds enough water for me to get through a half marathon.
However, one thing is that if you remove the neoprene sleeve to clean the bottle thoroughly, you must be very careful. The vented sleeve seems to be more prone to tearing. While putting the sleeve back on mine, it tore slightly. I think I will try to exchange mine since I've only used it one time. I feel the sleeve should be a little stronger and resistant to tearing.
Other than that, this bottle is perfect!

I bought this for running in the crazy AZ heat, but didn't end up actually using it until I signed up for my first full marathon (I've ran a bunch of half marathons). It doesn't slip off my hand and I don't have any issues with the weight of the water on one side of my body. I haven't tried other hydration systems and I would love it if I could carry more water with me, but I have no issues with this product. I like that I don't have to fiddle with a belt or backpack. It's easy to hold and to use.