Fisher space pens are used on all manned space flights for the American and Russian. They write at any angle (perfect for that pen hanging from a calendar), you can even write upside down. They write under water, over grease and in extreme temperatures. This model is an affordable, inexpensive version of the original space pen and the bullet space pen, both of which The Space Store carries. Writes -50 degrees farenheit to +400 degrees farenheit. Lifetime guarantee.The barrell color of the pen will vary with a chrome cap and black ink.