Just picked up the 20 and 30 oz. bottles. Light, strong, and reinforced at the (normally) weakest points in bottles of this geometry. Half and full-mark fill-lines make it handy to only fill with as much fuel as you need to, saving weight when you're on the trail. Been using them with my Whisperlite Int'l without issue. I've heard that the bottles have universal threading, so they can be used with other stoves, but haven't tested it. The child-proof caps are useful... in a house with children, but you can buy third-party non-safety cap that is weight rated, so that you can hang the bottle from it, if necessary.I will say this, you only really ever need 1 actual fuel bottle to be compatible with your stove. Any medium sized metal water bottle can serve as a reserve fuel.
"I have one of each size and love them. Recommend."
I have one of each and they're great. No leaks. they're relatively light and last forever. The small is enough for two days of steady use and the large probably four days of heavy use. I take a large and medium for a seven day hike and usually have half of the medium left when we hit the truck. get one.
"I think these actually create more fuel as you hike!"
So I picked up an extra bottle for a five day hike thinking I would need the extra fuel. After the first two days we realized that we had more than enough, this was nice since we didn't have to worry about using too much while heating some water to wash after a long hike or in the AM. These bottles are nice and solid, no leaks and light weight. Before we left to come home on the airplane I emptied and let it air out then used a stick lighter to ignite the residual fuel in the bottle. No damage to the bottle and the fuel was completely gone after a few minutes of burning, so we had no problem packing it in our luggage to bring home.
"Great bootles for all your fuel storage needs!"
I try to keep two of each size available for all my outing needs. The 11oz bottle is fine for me solo for a week on a single bottle, and the 20oz is good for two people for nearly 2 weeks if you are not boiling all your water. The 30oz bottles I take when car camping with large families and we are cooking and boiling water for cleaning, etc.I also use these to compactly carry fuel for all my other outdoor activities, gas for the chainsaw, emergency backup fuel for the ATV, fuel for my gas R/C planes, etc.The only word of caution is that these bottles are un-coated aluminum inside so they are not compatible with alcohol as the alcohol will pit the aluminum and contaminate your fuel and will eventually degrade the bottle making it unsafe. Check out MSR's website for more details. Other than that the are great!