Silver Bold Point Refill: The pressurized cartridge refills can be used in any pen from the Fisher Space Pen collection excluding the infinium and stick pens Write at any Angle: Fisher Space Pens are versatile and practical ballpoint pens that can smoothly write at any angle, even upside down with reliable performance on almost any surface Write in Extreme Temperatures: All Fisher Space Pens write in extreme temperatures ranging from -30°F to 250°F (-34° to +121°C), underwater, in space or any other harsh environment Quality and Reliability: Trusted by Astronauts, Explorers, and Professionals, Fisher Space Pens are often used in industries including Engineering, Aviation, Science, and Outdoor Adventures Explore The Fisher Space Pen Collection: Try our full collection of versatile and functional pens designed to write in Zero Gravity, Underwater, Through Oil and Grease and in Extreme Temperatures Fisher Space Pen’s Sealed Pressurized Ink Cartridge performs in temperatures from -30º F to +250º F, underwater, in zero gravity, at any angle - even upside down! The ultimate in dependability! Our PR Cartridge will typically write more than 12,000 feet depending on style and surface.