Inkjet cartridges incorporate complex technology and electronics allowing theme to fire thousands of drops of ink per second with great accuracy. In many cases the printhead and associated electronics are integrated into the cartridge making it essentially the printer. Each time you throw away a cartridge you are throwing away the most important and expensive part of the printer. In addition, most manufacturers incorporate a ” razor blade ” model where the printer is initially sold to the consumer at a discount while the profitability is recouped over time through the sale of overpriced inkjet cartridges. Refilling allows you to stop paying for the most expensive part of the printer just to top up your ink and to avoid overpaying for ink to pay-off for your printer.