It's essentially a plastic cylindrical shell over which there is a moulded rubber that is wrapped. There is nothing special about the grooves. All foam rollers have similar pattern.
I worked it on the glutes, hamstrings, calves and quads. Worked it on the neck also. It works fabulously well. Perhaps I was a little more overwhelmed than I should've but this was my first experience with the roller.
The roller, rather foam rolling, is recommended everywhere these days. It works by releasing myofascial tightness and knots in the muscles. This is what a masseur does too. My muscles felt really good after foam rolling for some time. I would recommend this for any one who does any physical activity. Only problem is you need a certain amount of physical fitness to effectively use it. Rolling it on the thigh muscles or glutes is not easy. One has to pivot the body on the palms and raise oneself and then gently roll up and down to effectively use it.
I saw an Amazon reviewer say that it broke for her. I don't know if she got a cracked specimen but my specimen looks sturdy enough.
