The Maxiflo Pump Action Ink Rejuvenator ensures the ink will not dry out - facilitating a steady flow right down to the very last drop of ink. (EG Pen Stands etc).
These are the best whiteboard markers you can buy. They are well made and last a very long time because they have an ink supply (much like a fountain pen has) that you simply pump when the felt tip starts drying out. I use them intensively because I teach. They last the longest, have low odor, and the tips stay together for as long as the ink lasts.
I can't understand how the other one and done markers are able to stay in business when the Pentel markers are available.