The new ECO version of the PowerTank is made largely from recycled materials. The barrel is made from recycled polycarbonate, while the grip area is made from a mixture of sawdust from Uni's pencil-making operation and resin - cutting down on the amount of new resin required.An interestingly-eco-warrior shade of green with a brown grip.The pressurised refill provides writing ability in extreme conditions. The Uni PowerTank will write on wet paper; upside-down; in temperatures down to -20degC; and even in zero-gravity. Just like a Space Pen - except the whole PowerTank pen is less than half the price of a single 'space pen' refill.