Roller Ball Pen by uni-ball® UBC60151 | OnTimeSupplies.com
Pen Set 10 ea Multicolored Rollerball Staedtler | eBay
RollerBall Pens, Shuttle Art 25 Pack(21 black 2 blue 2 red) Fine Point Roller Ball Pens, 0.5mm Liquid Ink Pens for Writing Journaling Taking Notes for School Supplies Office - Walmart.com
Amazon.com : 2PC STAEDTLER Cool Roller rolling ballpoint pen 411-2 red - Made in Germany : Office Products
my Staedtler 408 Sprint Capless Pen, G2 cartridges perfectly fits here : r/ pens