I don't know what they're called, or where to get them (sporting goods store? Target?), but when I was in high school, my mom bought one - it is weighted with inner ridges, and every time I used it, I ended up with bruises around my waist, so, if you bruise easily, look for one without inner ridges

i've tried searching for one but i really have no idea ...

http://www.amazon.com/Hula-innovation-workout-Hoop-Boxed/dp/B001...
This is the one my mom has

Here is one without inner ridges:
http://www.fitnessequipmentandmore.com/asp/superbrowse.asp?clid=...

Sports Authority (or a similar big fitness store) might carry them, if you don't want to buy online. I can also ask my mom when I see her later where she got hers.

Good luck!

awesome, thanx so much!! im ordering the unridged one :)