Package Included: 7 fountain pens with different size nibs (0.5mm/0.7mm/1.0mm/1.5mm/2.0mm/2.5mm/3.0mm); 36 pcs ink cartridges (6x Black, 6x Dark Blue 2 x Red, 2 x Deep Blue, 2 x Orange, 2x Yellow, 2 x Blue, 2 x Cyan 2 x Green ,2x Dark Green, 2 x Brown,2 x Purple,2 x light Purple ，2 x Pink). Ink Cartridge Size: Length - 50mm, Bore diameter - 3.4mm. Insert Ink Cartridge: Disassemble the pen and pull out the ink refill converter. You may be able to see a protrusion if you look into the grip section, this part is what punctures the cartridge and carries ink to the tip. Insert the opening of ink cartridge(cup-like rim) into the grip section, Push the cartridge in firmly until you feel the cartridge puncture. This may take more force than you expect. Customer Service: Your satisfaction is very important to us. If you have any problems, just contact us, whether you want to replace your order or want your money back, we won't let you down. This calligraphy set will help you develop your calligraphy skills, you can write a wide range of lettering styles with different pen’s nib. It’s a perfect gift for calligraphy beginners, it will help you enter into the wonderful world of calligraphy and creative lettering. Warm Tips: 1. Keep the nib at an angle, between 30° and 45° to the horizonal line of writing. This angle must be constant to achieve the beautiful thick and thin style of letter. 2. Wash the nib under lukewarm water after extended use and dry carefully. Do not allow the ink to dry in the nib as this will stop the flow of ink. Carry and store your pen upright to prevent leakage. Note: 1. Due to the many variations in monitors and browsers, the actual product colors may vary from colors shown on your monitor. 2. The trace of the combination of the nib and pen body is caused by glue bonding, not the ink residue.