Pilot fountain pen ink cartridges. Pack of 11! Color: Blue Black One has been used, so 11 remain. Brand: PILOT Style: Gel Ink Product Dimensions (L x W x H): 6 x 4.8 x 1.5 cm Item Weight: 0.05 pounds [How to use the cartridge ink] Remove the pen body of the fountain pen, point the nib upwards, and insert the cartridge. [How to use the cartridge ink] Insert the cartridge straight in without twisting. [How to use the cartridge ink] If the ink doesn't come out after inserting the cartridge, gently squeeze the cartridge from both sides to send ink to the nib, and it should start writing smoothly. Will be packaged in simple packaging. Please purchase only if you understand that this is a used item.