Let's get the famous story out of the way first. Everyone 'knows' that ballpoints didn't work in space, without gravity, so the Americans spent millions of dollars to develop a special pressurised ballpoint that did work in space. The Russians just used a pencil. Well, not really. The Americans and Russians both used pencils. Paul Fisher, an inventer and pen maker, developed the pressurised refill, creating the 'Space Pen'. Then both the Americans and the Russians bought them from him and used them in space. Graphite is conductive, so snapped off bits of lead were considered a bit of a safety hazard floating around in a space capsule, so they were glad of a good alternative. Oh, and standard ballpoint pens do work, and astronauts do sometimes use them, they're just not as reliable in zero gravity and extreme temperatures. But Paul Fisher's Space Pen was reliable in these conditions, which makes it useful in all sorts of conditions, not just in space. They'll write better on damp paper, and greasy or dusty paper. They'll cope better in freezing conditions or excessively warm conditions. They have a much longer shelf life than standard ballpoints, too. They're just more reliable here on Earth, as well as in space. It's these refills that give the Space Pens so many of their great features - the reliability, and the ability to write upside-down, on wet, greasy or dusty paper. They have a long shelf life, and last for a lot of writing. This version is the standard refill for almost all Fisher Space Pens, and is supplied with a small plastic adapter that allows it to work in almost any pen that uses 'Parker-style' G2 refills.