The TWSBI EcO Fountain Pen features a clear demonstrator barrel that showcases the internal piston-filling mechanism. It has a smooth-action piston filler and is adorned with chromed metal trim and a pocket clip. The cap is topped with the TWSBI logo and features a rubber o-ring for an airtight seal, preventing ink drying and ensuring the cap is securely attached. Its faceted cap design prevents the pen from rolling off surfaces. The polished steel nib is engraved with the TWSBI logo and branding, and is available in extra-fine, fine, medium, broad, and 1.1mm stub sizes. Please note that piston-filler pens do not accept cartridges. The pen comes in gift packaging and, like all TWSBI fountain pens, can be fully disassembled for cleaning and servicing. Instructions and necessary tools are included, though disassembly is recommended for experienced users and not required for regular use. Disassembly is performed at the user's own risk.