BAHA!! that's actually a pretty good question, because normally they'r too cheap and crappie,, is this for shooting sumone? or a pool party?
Here's that one and more if you can't find that model: http://en.wikipedia.org/wiki/Super_Soaker
here's a link, I did a little research for you and all the things I read pointed to this gun. its kinda old so you'll probably have to look for it on ebay
Arent water guns for little kids?
nope, lol, they are FUN! you GET INTO WATER FIGHTS, IT'S AWESOME