Composed of anodized aluminum with pressurized black ink pen and a medium point The Backpacker pen can hang upside down forever yet function immediately when needed Like all Fisher Space Pen products: the Backpacker pen will write upside down - at any angle, under water, through grease, extreme temperatures (-30 to +250 degrees F) Easily attaches to keys, backpack, belt loop, hiking gear, fishing sling, camping equipment and much more Made in the USA and has lifetime guarantee for quality against all manufacturing defects