the clay mitt also same as the clay towel: 

BT-6016: it made by microfiber towel with clay 

BT-6026: it made by 

Brilliatech take the different clay of the microfiber towel, mitt and change thickness of the material to achieve more removal power.  
Fine grade of the clay towel: it is a kind soft clay on the towel,it can removal contaminants well.
Medium grade of the clay towel: it remove the contaminants easy and fast. 
Heavy grade of the clay towel: it is almost same as medium.we just adjust the thickness of the clay and towels. 
The King series are use a new material,it more smoon and the cost also higher that fine, medium and heavy. 
King1: a new material with the clay, let it more removal power. clean the paint surface easy and quickly. 
King2: King2 and King3 almost same, but the clay on the towel is differnt surface. K2 more dense of the handle feeling.
King3: handle feeling more smoonth and the removal power is very good.
Point: Point type clay on the towel or mitts.  different customer different feeling