our company produces the erasable pen with magic effect. It can be removed easily with common rubber within 2-4 hours, and erasable effect is beyond 95%.Then beyond erasable time, the ink can remain forever. Hangzhou WenDu Stationery Ltd.china Address:No.1701,1-17,Fengqi Yuan,Fengqi Road,Hangzhou,China Tel:86-571-87295679-12,87292817 Fax:86-571-87295679-13 http://www.chinapen.cn http://www.wanjia-pen.com.cn Email: partner@wanjia-pen.com.cn shirley