Amphipods

Does anyone use these? I will also be posting this in the Tri section, but I was wondering if anyone has used these and if they are worth getting. I hear good things about them and I am looking for an easy-hold water bottle.

http://www.banderasnews.com/0612/ima...algadgets2.jpg

I use one very similar, by Ultimate direction. I prefer the ease at which the water comes out. First time running it felt weird, but now I like havong it with me and do not notice it.