stainless steel or polypropylene?
For some reason, I thought a polypropylene flat cap came standard with the Klean Kanteen water bottle which is why I bought this stainless steel loop cap. I was surprised when my water bottle came with a stainless flat cap. Nevertheless, I like the loop cap better than the flat cap. It is easier to screw on and off and to carry the bottle with. It is too expensive though. Make sure you order it with the bottle at the same time so you don't have to pay for extra shipping.

Do not submerge
I ordered these as replacements to the plastic lids that came with my kanteens. They came with a "Made in China" sticker on them, so I soaked them in the sink to get the stickers off. They wanted to float, so I had to put something on them to hold them down in the water. A couple of hours later (I got distracted!), I picked them up to scrape off the stickers, and what do I hear but sloshing water... the lids had taken in water, but there was no way to open them up and get it out. All I could think was that the soapy water would be slowly leaking into my drinking water. So... it was back to the plastic lids Klean Kanteen Loop Cap/Polypro for us! (BTW, HealthEGoods was very helpful about returning them).

Get this- don't settle for plastic
I decided after getting the Klean Kanteen 27 oz bottle, to switch from a plastic to the s.s. and HIGHLY suggest it. Water tastes super clean and fresh with the s.s. and using a plastic cap where you drink from ruins it. So worth it!

Loop Cap
Was realy torn whether or not to use the cap that came with the bottle or to order the stainless cap. Caps do touch the water so the right decision is to go stainless steel all the way. Excellent product and excellent service.

Plastic free
My doctor recommended that I read a book called What Your Doctor May Not Tell You About Breast Cancer by Dr. Lee. Because of what I have read in that book and the health risks revealed about BPA and how plastic leaches estrogens into our food and water when it gets warm, I am on a mission to keep my food and drink from touching plastic. Klean Kanteen's 40oz bottle is the perfect size for me to take my filtered water from home with me so that I can stay hydrated at school--its most of my water for the day. Aluminum changes temperature quickly, so if you like cold water you might want to consider purchasing the insulating sleeve that Klean Kanteen makes. It works great for me and has helped me take charge of my health. The rest of the teachers at work have asked me where I got my super cool water bottle and want to switch to stainless steel too. Klean Kanteen is the only stainless steel water bottle that I have found that also has an all stainless steel cap so that you can be sure that no plastic comes in contact with the contents.