The Blue Roller Gel Refill for Cross, fine tip (F), is compatible with Cross rollers, allowing you to maintain the smooth and fluid writing experience characteristic of these pens. The high-quality gel ink glides smoothly over the paper, almost like a fountain pen, and the fine tip ensures a precise line, ideal for detailed writing or small handwriting. It's a practical and economical way to extend the life of the roller without needing to replace it entirely. The blue color is the most versatile for everyday use, suitable for note-taking and correspondence.