Crystal Bottle of Kales'Oh

A Crystal Bottle of Kales'Oh (カレス・オーの水晶瓶) is a multi-use item that can be used to store the proficiency of an equipped skill to open up a skill slot without losing progress in the removed skill. The bottle is a possible drop from a Forest Elven Hallowed Knight that can be encountered as part of the first chapter of the Elf War campaign quest on the 3rd Floor of Aincrad in Sword Art Online.

Official Description
English = This bottle allows you to save the proficiency of any skill currently equipped in a skill slot. Japanese = この瓶には、スキルスロットに設定中の各種スキルの熟練度を保存することができます

Usage Notes
Before the bottle is used, the user needs to use the properties window to select the skill they would like to store in the bottle. A skill already stored in the bottle can be retrieved by pulling out the stopper and inhaling the light-turned liquid inside the bottle. To store a skill already equipped, the user exhales their light-turned skill into the bottle, and the light turns into a liquid, the colour of which depends on the stored skill.