The TWSBI ECO (short for "economical") provides the same high-quality, high-capacity piston filler as the TWSBI Diamond 580 at an even lower price. It features a sleek, transparent barrel and a hexagonal screw-on cap that can be posted securely on the back of the pen.

The pen comes in an attractive clear plastic case with a clean, modern design. For protection, the plastic case is packaged in a cardboard box.