This is the Fisher Space Pen Co.'s cap-action ballpoint pen "S251". This pen is known for its ability to write in harsh environments where ordinary pens cannot, such as in zero gravity or underwater. Here are the product features: * Writes at any angle due to a special structure that extracts ink using nitrogen gas pressure. * Operates in a wide temperature range from -31°C to +121°C. * Can write on wet paper and paper soiled with oil. * Sold in NASA and Smithsonian Museum shops. - Model Name: Fisher Space Pen Cap Action Ballpoint Pen "S251" - Color: Black - Materials: Metal and plastic Thank you for viewing.