If you haven't felt a roll of this on your body before, than you haven't had a life yet. This is something....
This one is named trailer truck pinwheels simply because how many wheels you have and how they are aligned. You have 10 wheels in total, each on individual differential, assembled on 2 axis with 5 wheels on each. Both of the axis are locked on to the main body with another differential, allowing a 360 degree spin. this is especially useful when you want your wheels to equally distribute force and be in a constant grip with the body around the curved parts, such as neck, head, boobies, ass or the sides.
As soon as you lay down and your partner just rolls this up and down on your back, you're gonna be feeling pleasure of a kind that you have not felt before. Your muscles will spasm because of how pleasant it is and you will want more. This small tool is an ideal start for BDSM game. As soon as you orgasm after sex, you're gonna feel the calmness going throughout your entire body, through these muscles, putting you into a complete relaxed state.