This is the replacement pressurized refill cartridge for the Fisher #Q4 Multi-Action Space Pen and it can also be used in various standard ball pens and the Troika Construction Pen. When the pressurized universal cartridge arrives, it will be long in size. It is made this way to fit several different pen barrels. If you need it to be shorter, just flex it back and forth at the break point and it will separate, leaving you the correct length refill. Please note: these universal pressurized cartridges contain a much smaller amount of ink than the standard Fisher Space Pen refills; they write about 1200 feet (365 meters) depending on your writing style.
The Pressurized Universal Refill Cartridges are sealed pressurized refills which do not leak, have a shelf life of over 100 years, write in a vacuum, upside down, under water and in extreme temperatures, in freezing cold and bitter heat.