OASO 24pcs Fountain Pen Ink Cartridges, Fountain Pen Refill Cartridges 3.4mm Bore Diameter (Blue (Heat Sensitive Erasable Ink))

OASO 24pcs Fountain Pen Ink Cartridges, Fountain Pen Refill Cartridges 3.4mm Bore Diameter (Blue (Heat Sensitive Erasable Ink))

• This is heat sensitive erasable Ink cartridge, fit for erasable fountain pen with 3.4mm bore diameter, such as OASO K019 fountain pen (ASIN: B0CR5ZDQHP).
• Cartridge Lenght:51mm; Cartridge Diameter:5-8mm; Bore Diameter:3.4mm.
• There are 4 packs, 6pcs per pack, 24pcs ink cartridges in total.
• Please remove old Ink cartridge first, then stab the small part of the ink cartridge to the pen body (you will feel and hear a "click" which means the cartridge installed in right place), and please wait a minute for let the ink flow to the nib. If did not work, please change one other ink cartridge to try again.
• If any troubles about our pens, please feel free to contact us, we are glad to solve any problems with you.