These double walled stainless steel bottles are 17 ounces. The opal design is beautiful and it fits easily into my purse or cup holder on the go. Water stays cold all day in this!! I use these now for just about everything when I travel. Even in my bag it doesn't leak at all. I am really enjoying these and I drink more water also because I always have one with me. You won't be disappointed! #blogbooster, #review booster, #rankbooster, #reviewgal, #YChenportablesportsbottle