Other Sound & Hi-Fi Edding

How is it possible to open the cap of a marker with one hand when i.e. holding a ruler to a whiteboard? Simply by not having to do it! The particular edding 12 whiteboard marker offers a retract system which can be operated with just one hand like a ball pen. The round nib reveals itself only after pushing a button. But that's not all the ink can easily be dry-wiped off any whiteboard without leaving any residue.
The ink also works on other non-porous surface like enamel glass or melamine. This quick-drying and low odour edding is a very convenient solution not only because of the single handed use but furthermore because caps will never get lost again.