TWSBI ECO Irish Green and Onyx Fountain PenThe TWSBI ECO fountain pen boasts an incredible value with its piston filling system and affordable price. Like many other TWSBI fountain pens, it features a crystal clear acrylic barrel so you can see your ink level, and an irish green cap and finial. The pen cap has an inner cap to ensure a perfect seal when stored away. It is completed with black onyx trim and a black stainless steel nib. TWSBI's belief is that it is important to allow the user to