King and Sun Tiger stones are made by Matsunaga Stone Co. LTD in Osaka City Japan. These are one of the most Popular Waterstones in Japan.
The King Stones are a great choice for standard steel and Stainless steel knives below 59HRc. The abrasive is not strong enough for High Vanadium content or very hard steels except for the 220 grit or the 250grit side on the dual stone. This is made from Green Corundum and should be fine with all Hard and high carbide steels.
The Sun Tiger 240 grit stone is made from Green Corundum which is the second hardest natural mineral and should have no problems with any steel.
The King Hyper and Neo stones should be able to handle the harder and higher Vanadium content steels. Hopefully we will be able to get these in the future. For now the best choice is the Suehiro Cerax and Debado, Arishiyama, and Kitayama stones for those steels.