Unique Serial-number for every AS -Ⅱ.12-Month Product Warranty. Practical Design - Full bounding key stick gasket for longer life and better pressing feel. Keystroke link: all being applied oil for debugging before leaving the factory, preventing the link from rusting and getting stuck.Setting the F# key to suit the performance.The U-tube of the bass is adopted: has accumulated crafts experiences for many years to improve the stability of the bass and achieve a stable feeling of playing and resistance.