The printer cartridge is an ink or toner substance that prints paper. It is an irreplaceable component of the printer. The primary function of a cartridge is to offer a reliable, cost-effective and efficient method of supplying ink, toner, or other material to printers, which is then used to produce the printed page upon demand. https://www.cartridgesave.co.uk/toner-cartridges/Canon/i-SENSYS-MF-237w.html