I got the top of the line Astars one. Comes with shoulder straps and a waste band thing. I was worried about the fitment under my leathers because I like my leathers tight. But it still fit. Personaly, I like spine protectors. They help my form out. Line my upper with my lower. I don't have any complaints about it. It was right around 100 degrees that day too. Didn't bother me.
http://www.google.com/products?hl=en...&um=1&ie=UTF-8