The black ones you see pretty much anywhere get it done. http://www.amazon.com/Black-High-Density-Foam-Roller/dp/B00QAX3NYG
The white ones break down a lot quicker and are much softer. At 180lbs I have a hard time getting deep enough into my tissue with anything too soft, but the black foam gets it done just fine.
Pick a foam roller up, use it religiously. Also stretch properly before and after activity. Strengthen your thighs, especially your vastus medialis.