Its a fine bar of clay that removes surface particles that embeds itself into the clear coat. When those particles are present wax doesnt bond properly. This is my first time using a clay bar. I usually just threw a coat of wax on once in a while and called it good. Being that both of our cars are new I wanted to start them off right so to speak. To give you a better idea of the surface particles I am talking about, next time you are around a freshly washed car run your nail bed along any area of the paint. It should feel like glass, if the car hadnt been clayed you will feel a bunch of bumps on your nailbed. This is the kit I used, $17 at Wally World.