I use this sanding grit system all the time to take a gourd from a just clean surface to an incredibly smooth, polished and exquisite finish.  There are 5 different grits of sand paper included in the set.   As long as you clean them with the "stick" they will last 10 - 14 times longer than non cleaned sand paper.  These discs are designed to fit onto the "Flex Wheel" after the Hook is applied for a quick change of grits. 

Color of sand paper may vary.