This STABILO OHP Pen is an overhead projector pen with a medium tip non-permanent ink. Writing in water-soluble ink, this STABILO OHP Pen can be used on most smooth surfaces, and is ideal for writing on clear acetate for use in overhead projector presentations. This OHP Pen has a medium tip, handy pocket clip, and if you accidentally leave the cap off it will take 3 days to dry out. Featuring a non-slip grip for added comfort, this acetate pen enables easy, tension-free handling.The STABILO OHP Pen is perfect for presentations at work or university, or for teachers using projectors in the classroom.. Writes on almost all smooth surfaces . STABILO quality for a variety of uses - from fine writing to clear marking . Black shaft indicates permanent ink. Grey shaft indicates water soluble ink . Ideal for any transparency. Non slip grip zone and practical clip. High Cap off time of up to 72 hours!