Because the child has to suck up the formula, I think it made the transition from bottle to straw a breeze.
You can purchase the entire bottle and hands free kit...
here to learn more and you can visit here to find a location that sells the bottles and/or adapters.
I did a quick search on Amazon.com and found the bottles for $9.95 and the adapter kit for $7.95.
I can only imagine how this would make life so much easier for a parent of multiples!
This is a picture of baby Jared and his hands free bottle: