This kit can help keep your tubes from freezing when temps dip down. If you are backcountry skiing, hiking, or snowmobiling or any other winter sport, you might consider adding this accessory. The main downside is the price: $20 is a lot considering the entire CamelBak Antidote Reservoir can be found for $25-35. Also, it may not keep water from freezing in the tubes during really cold conditions. Even with this thermal control kit, you still may need to use the old trick of blowing the water pack out of the tube after each drink. This clears the lines so there is no water to freeze. This kit also does nothing to insulate the actual bladder.
This works with all CamelBak bladders with the modern quick clip attachment. It also works with a number of other brands that use a similar attachment including some models of Geigerrig and Platypus bladders. Even if your hydration bladder does not have the same attachment point, you may be able to swap it in. Or maybe not, it will vary from case to case.