Fisher Space Pen Red Ink Fine Point Universal Cartridge Red ink fine point Fisher pressurized universal cartridge. This is the replacement Cartridge for #Q4 Multi-Action Space Pen. Please note: the SU Cartridges contain a much smaller amount of ink, they write about. 1200 feet depending on your writing style, as compared to our regular PR Cartridge. which should write more than 12,000 feet depending on style and surface. Features: - Replacement cartridge for Q4 - Ink Color: Red Ink - Point: Fine Point - Write about 1200 feet depending on writing style - Note: SU cartridges contain smaller ink amount