The Fisher Pressurized Refills is the Fisher standard 3 1/2 inch Pressurized Cartridge that fits most of the Fisher Space Pens. The Write Out for this Cartridge is approximately 15,000 feet depending on writing style - 3 ½ times longer than a typical ball point Cartridge. Designed for NASA space missionsthis unique pressurized refill write upside down, under water, in gravity free space, over glossy surfaces and in extreme temperatures.

Fisher Space Pen - Refills - SPR4 Pressurized Cartridge - Black Ink -  Features:

• PR Series Pressurized Cartridge Refill
• Writes Upside Down & Underwater
• Brass & Steel Construction
• Includes: Parker Adapter
• Color: Black Ink
• Point: Medium Point
• Blister Card Packaging