In all rollerballs that take Classique rollerball or fineliner refills, the Montblanc ballpoint refill including extension plug also fits without an additional adapter. With slim Slimline models a self-built adapter would be necessary. With cramped writing posture and strong pressure, however, the slim form is not recommended; rather a thicker writing instrument like the LeGrand rollerball, since this reduces cramping. For left-handers the ballpoint is usually the better choice but should still be sufficiently thick. With some rollerball models like the Meisterstück Platinum Line Classique Rollerball the local dealer denies compatibility, which is to be checked individually.