It's filled with Pilot's unique thermo sensitive gel ink that flows smoothly and consistently. The heat generated by friction when rubbing the paper with the rubber tip of Pilot Frixion pen turns the ink invisible.
3x FRIXION Point Knock Synergy Tip REFILLS Needle Pen Erasable Ink Pilot 0.4 XF
Pilot FriXion Ball Knock Zone - 0.5mm First Light Pink
Quick Dry Inks 0.5mm Gel Pen Refill Liquid Inks Pen Refill
Stabilo Pen 3557 /3555 Transparent Mechanical Pencil 0.7/0.5
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10Pcs 0.38mm Gel Ballpoint Pen Refill Black Blue Red Stationery
Pilot FriXion Ball Knock Click Retractable Erasable Gel Ink Pens,Fine Point, - 0.5 mm - Black,blue,red,blue Black Ink- Each 1 Pen- Value Set of 4
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Stabilo Mechanical Pencil With Lead And Free Eraser 0.5mm/0.7mm
PILOT FriXion Erasable Gel Pen Fine Point LFPK-25S4 Refills 0.4mm Many Colors School & Office Stationery - AliExpress
PILOT FriXion Ball Knock Erasable Ballpoint Pens, Refillable & Retractable Gel Ink Pens, Fine Point, Assorted Color Inks
Quick-Drying Gel Pen for Office, School, and Stationery – CHL-STORE