<p>A unit of ink cartridges including at least three types of ink cartridges having different sizes is provided. Each ink cartridge has a first casing member and a second casing member. A first ink cartridge is larger in size than the second ink cartridge, and the second ink cartridge is larger in size than the third ink cartridge. The first casing member of the second ink cartridge is the same as the first casing member of the first ink cartridge, and the second casing member of the second ink cartridge is the same as the second casing member of the third ink cartridge.</p>
