Rollerball pen refill with blue ink delivers a rich, sophisticated color for an optimum writing experience that's convenient and practical. Medium-point nib creates bold, solid lines for greater visibility on pages. Smooth-flowing design lays down effortlessly to produce consistent, fluent lines. Easy-to-use design allows you to quickly replace your depleted pen for quick, simple use. Ink cartridge is designed for all Parker rollerball pens (sold separately).Rollerball pen refill with blue ink delivers a rich, sophisticated color for an optimum writing experience that's convenient and practical. Medium-point nib creates bold, solid lines for greater visibility on pages. Smooth-flowing design lays down effortlessly to produce consistent, fluent lines. Easy-to-use design allows you to quickly replace your depleted pen for quick, simple use. Ink cartridge is designed for all Parker rollerball pens (sold separately).