The rollerball refills by Waterman contain high-quality ink that is smooth flowing and long lasting. Waterman Rollerball pens produce flawless lines. It's an anytime, anywhere ink that gives smooth writing to your spontaneous expression. For use with Waterman rollerball pens Blue ink Fine point Size 4 3/8 inches x 1/4 inch (111 mm x 6 mm) Designed and formulated with superlative ink flow to assure superior writing smoothness and bold print quality.