MengRan 2.75'' Ballpoint Pen Refills for Diamond Crystal Stylus Pens and Ballpoint Pens,Metal Refill,Black Ink,(Pack of 10) Black ink, 0.7MM Core. 2.75'' Length. Smooth writing. Suitable for all MengRan's ball pens except new style!!!!!! refills for swarovski pen and other brand diamond crystal stylus pen. Black ink, 0.7MM Core. 2.75&#039;&#039; Length. Smooth writing. Suitable for all MengRan&#039;s ball pens except new style!!!!!! refills for swarovski pen and other brand diamond crystal stylus pen. The refills are also suitable for tactical pen.