A blue toner cartridge is a consumable material used by a printer or MFP. Contains toner - laser printing powder, which is used to form images in the xerography process. Consumable life is the maximum number of prints that can be produced using a given consumable. The resource is indicated in A4 pages at a certain level of toner coverage, usually 5 percent. Percentage page coverage is the ratio of the area of the page areas filled with toner or ink to the total surface area of the page. So, 100% coverage is a black A4 page completely filled with toner.