Your Lamy rollerball refill determines the way your Lamy rollerball pen writes. Perhaps that why you love this pen so much. We carry two varieties of Lamy rollerball refills, the M63 and the M66. Both are offered in a fine point in black, blue, red or green ink.The Lamy Swift and Lamy Diaglog 2 rollerball pens fit the M66 refill. Lamy Safari, Al-Star and Studo rollerball pens use the M63 refill.