The Red Ballpoint Pen Ink Refill extends the service life of compatible pens and provides an economical option for schools and offices managing high stationery consumption. Red ink is widely used for marking, corrections, approvals and document review. Specifications: standard slim ballpoint refill, red oil-based ink and approximately 10.5 cm length. Compatibility varies by pen model; users should compare refill length, tip shape and barrel fitting before purchase. Bulk packs are suitable for teaching departments, examination teams and administrative offices.