JINHAO ink cartridges fit for most JINHAO and Baoer fountain pens, EXCEPT JINHAO 35, JINHAO 65, JINHAO 619, JINHAO 80, JINHAO 10 and JINHAO 519 Quantity: 30pcs in 6 boxes of small carton Lenght:52mm; Cartridge Diameter:Appr 4-6mm; Bore Diameter:2.6mm Please remove the converter(ink pump) from the pen 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 problems caused(like did not receive or pen did not work), please don’t hesitate to contact us, we will try our best to help you solve the problems We are the professional pen store, you also can find the other great pens in my shop