Dear DFW_Tri

SpeedSip has a generic cap-bottle thread that will work with the majority of the bottles but I can not guarantee that it will fit to all the bottles.
Simply, there are too many variation.
That is why it will be produced as a complete matching unit: cap + bottle.

Nevertheless, I tested several brand bottles with SpeedSip cap. Some of them are ok, some of them not. Here is a short list:

CamelBak = OK
Polar Bottle = OK
Specialized Purist = OK

Performance = NO
ZEFAL (Eropean) = NO

The other issue is the bottle + cage compatibility. The situation is even worst. The concept of "rocket launching behind the saddle" is well known.
I selected the bottle shoulder design that fits well to a good quality cage (like Blackburn Cinch) with no issues on a bumpy road or railroad crossing.
Please send me an e-mail for the details.
Thanks.