Pilot frixion pens have been my go to fabric marker for a few years now. They have a 0.7mm rollerball nib and the blue ink is erasable - either by
Japanese Pilot FriXion Erasable Tricolor Pen
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Marking Pen - Blue or Black Frixion Heat Erasable Gel Pen – Lolli and Grace
PILOT FRIXION CLICKER: This pen combines the ease of a retractable pen with Pilot's erasable thermo-sensitive gel ink. No wear or tear so you can
Pilot FriXion Clicker 0.7mm, Erasable Gel Pens, Fine Point (6-Pack, Black/Blue)
Why Pilot FriXion Pens Are Every Parent's Back-to-School Bestie
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FriXion Erasable Gel Pen - Choose Your Color – Whimsicals Paperie
Review: ALL The Erasable Pens (Pilot Frixion + Uni Fanthom) - The Well-Appointed Desk
Pilot Frixion Clicker Pen (Navy) – Carolyn Friedlander