Gelion 1 Gel Pen Feed mechanism: push mechanism. Refill type: Gelion 39 (ISO format G2). Ink type: gel ink, indelible. Refill design: wear-resistant stainless steel tip, 0.4 mm, black, refillable. Can be left open for a few days without drying out. Pen design: plastic, rubberised, clip material: plastic. Schneider ballpoint pens and refills with the plug and play symbol are compatible with each other. This makes changing leads easy. Barrel colour: black-transparent / black.