Hongdian Fountain Pen Yellow Ink Cartridges Set of 30 Refill Ink Cartridges 3.4 mm Bore Diameter

Notice: These cartridges are not Standard Size, Please ensure your fountain pen takes 3.4mm bore diameter cartridges. You may like the cartridges syringe filler converter below: www.amazon.com/gp/product/B08LLFVQVV How to fill a fountain pen with cartridges: Insert the narrow end of the new cartridge into the black of section block with enough pressure to create a snug fit. The pin inside the section block will puncture the seal of the cartridges, allowing ink to flow into the section block. Screw the barrel on over the cartridge into the section block. When you fill the pen at the first time, you can swing the pen to make a few drops of ink coming out of the nib, so that it can flow easily. Customer Satisfaction If the cartridges you received are not in satisfied condition, please feel free to contact, we will fix the problem for you.