Gel rollerball refill Gelion 39. Use for product: Gelion 1 gel pen as well as in all Schneider ballpoint pen models with universal plug + play fit. Type designation of the refill: Large-capacity refill G2 format. Type of writing fluid: gel ink, ISO 27668-2, document-proof, lightfast, waterproof. Mine design: wear-resistant jumbo point made of stainless steel, 0.4, blue. Writes easily and fluently.