Unlike most other pens, overhead projection pens are not water-based, but solvent-based. They come in water-soluble and permanent versions, with different tips and varying degrees of light and frost resistance. Because they are solvent-based, they can also be used to write on most smooth surfaces such as glass or foils.
The STABILO OHPen permanent has a black barrel, while the STABILO OHPen water-soluble has a gray barrel.
The plastic tip is very resistant and therefore you write clearly even on hard surfaces. We have tested this on over 1,000 surfaces such as glass, plastic, photos, CDs, DVDs, ceramics, foils or metal. It also holds up under extreme conditions such as cold, heat or rain. That's why the STABILO Write-4-all permanent marker is also approved for freezers or greenhouses.