As we talked, our clay system have 9 grades with 3 series.  

King series have 3 grades, K1,K2,K3 magic clay bars

King sytem magic clay bars developed base on fine, medium, and heavy clay bars
King one(K1):  nice hand feeling, and good for car washing details.  
the item numder is BT-2015K1
King one(K2):  more powerful and good for car washing process. 
the item number is BT-2015K2
King one(K3): K3 is not only good hand feeling,also very good for removal powerful.  
the clay bar item number is BT-2019K3

The K3 develop in 2019, and pass the all test, mass production in 2023.  
New concept about the clay bars......