Silver Medium 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.