Instruction: Extract information from the supporting document to answer the given question.

Input:
Question: how many ounces do they hold?
Document: I bought a pair of these at Costco about a month ago and after only a few day's regular use, the rubber part the straw fits into already had a small tear in it. Also, the part where the straw actually fit into the rubber did not seem to hold its seal very well.
It should last many years that way. This doesn't work for carbonated drinks or hot drinks. It also doesn't work on a plane. When I opened the spout while flying, it shot liquid through the air. These bottles truly keep drinks very cold for almost 24 hours.
I LOVE THESE. I really like to drink water but really, really, hate warm water. This keeps it cold for a long time without the need for ice ( which is nice because i have no icemaker) . The only downfall is the smallish volume capacity, I wish it could hold more. but besides that these work great!! My husband keeps stealing them.
*  Make the carrying loop like a &#34;D&#34; ring Carabiner clip that opens so you can clip it to stuff. *  A stainless steel straw option? That would be nice, then there would be NO plastic touching my water. *  I wish it could hold more liquid but that would probably mean it would have to be much bigger (because of insulation), so I'm not sure I'd even change that.
These water bottles. They are amazing. They are durable and attractive. I like my beverages ice cold and these extremely insulated bottles can keep ice intact for hours and hours (10 to 12). The mouth is also wide enough in which to fit ice cubes, which is a necessity for me.They might be a bit bulky for some (and not hold as much water because the insulation takes up some space), but for me, keeping my water cold far outweighs this inconvenience.
My daughter has been using the bottles for school since September 2012 and in the last few weeks the straw has stopped working. She has to take off the cover to drink the water. I remove the straw every night to rinse it and am not sure if that is the reason for the malfunction. Please advise. These bottles were too expensive  with too many positive reviews to last for such a short time. If I can reverse whatever damage has been done, do tell!!!
These are the perfect water bottle! After wasting money buying many other water bottles, my daughter found this one. I carry it with me and use it every day! In the morning I fill it with ice, and add water (I add a little bit of crystal light). The ice keeps it cold all day! I just refill my water and I'm good to go! I recommend these to all my friends.
I bought 2 of these over a year ago and drink 128 ounces of water per day out of it and so does my wife, I keeps the water cold and has worked flawlessly, the straw comes loose occasionally from turning it against the ice in the container, and thats maybe once a week, great product I'm just surprise Costco has it so much cheaper than Amazon.
Hooray! These are just what I was looking for. Even if left in a hot car for several hours, the water inside stays cool. They are sturdy and good quality. I love that the drinking spout is covered until you push the button. The mechanism works well. So nice to be able to grab and drink in the car while never taking your eyes of the road!I was frustrated when ordering them that I couldn't find their capacity. The bottles are 22 fluid ounces.
wonderful product. Beverage stays cold, ice doesn't melt, and there is no condensation. ANd best of all, no metal taste.
Answer: Those I believe are 21 oz.