Review on Black Elite 0111804 Byasi Water Bottle by Kenny Marozas

You can use a water bottle but it is much better designed and doesn't have the narrow neck that many water bottles have. Makes packing and accessing contents a lot easier, and there's a separate inner cup for small parts or things you want to protect and find easily. Much better than a saddle bag because the weight of the bike is lighter and it doesn't increase drag. If you don't need to carry two water bottles (i.e. your rides are less than 1.5 hours or you have the option to refill your main bottle mid-ride) then it makes sense to have a second bottle cage for tool storage.