[1]it is the improveing pen of air erasable pen.it is good for the normal air erasable pen. [2]environmental protection,not any poison [3]silver refill pen is used by leather mark normal.at the same time it can used by any material. [4]it is not disappear automatism for the writing.but it will disappear between one to ten days,or after the writing touch the water. [5]we have multi-design. [6]outer cover are brass and nickle warning [1]silver refill pen is the same with disappearing ink pen and auto vanishing pen in some condition. [2]use the air erasable pen in its available time. [3]please use "the water" or "clearning pen" to get rid of the writing,if the writing do not disappear on normal situation. [4]the disappear time is limited to the material,air wet condition,temperature, and so on.