Kung is a revolutionary yo-yo. It is the first metal off-sting yo-yo made with high-precision CNC lathe. The body is one forming metal part. The material is 6061 T6 aluminu ally. This material is widely used in aircraft and spacecraft. It is a high strength and light material. The outer plastic rim was designed by precise computer simulation. By the Finite Element Analysis, we found the best thickness and material. It is easy to catch the yo-yo, although is dropped on the ground. And the plastic rim can protect the metal body. Besides, there are thumb grind rim. You can do much challenging thriks you though. The response system is exclusive axle system the by Yonity. It provides best response and smooth. The bearing is 5X11X5 mm. This smaller bearing give you batter response when you doing regenerate tricks. Furthermore, the gap is adjustable. No matter what the string-trick or regenerate tricks, you cam adjust the gap to achieve the best feel you want. Anyhow, Kung is definitely an unprecedented revolutionary yo-yo. It is no longer just an enlarged 1A yo-yo. It is the genuine high-tech yo-yo designed by real mechanical design process by the engineer of Yonity.