Ten year ago I discussed the humangear capCAP. My conclusion was: the capitalization of the brand and product name is stupid, the cap itself is a good upgrade to any wide mouth (63mm) bottle, but it will allow a few drops to leak out of a wide mouth Klean Kanteen.
Recently I was made aware of a new model: the humangear capCAP+. This one adds silicone gaskets to both parts of the lid, and boasts compatibility with a wider range of bottles. However, humangear explicitly states that this one remains incompatible with the wide mouth Klean Kanteen.
I like to live dangerously, so I bought the new model anyway. For a couple weeks now I’ve been using it on the same Klean Kanteen Wide 27oz bottle used in the previous review. Despite humangear’s warning, I have had nary a drop leak out from the cap. I have tried to make the lid leak by filling the bottle and storing it on its side, and by balancing the bottle upside down on the cap, but no water has escaped.
Other changes in the new model include redesigned grip cutouts, which I find to have made no practical change to the functionality of the cap, and a cap retention thing that I thought would be kind of a gimmick but is actually surprisingly useful. (I will point out that the full name of this feature is the “humangear capCAP+ CapKeeper”. Someone at this brand hates English.)
The new model weighs 56 grams (2 oz), which is 20 grams (0.7 oz) more than the original capCAP.
I’m happy with the capCAP+. If you have the original capCAP, and it doesn’t leak on your bottle of choice, it probably is not worth upgrading. If it does leak, consider trying the new one. If you have neither model, but you use a wide mouth bottle and rely on something like the Guyot Designs Splashguard, the capCAP+ may improve your life.