In laser printers, the drum is used to transfer the file image onto paper. The surface of the drum is charged selectively by a laser, based on the pattern to be printed. When brought in contact with the Toner, the charged areas attract the toner particles to complete the pattern on the drum. When the paper is rolled over the drum, the pattern is transferred on to it. In many entry level models, the Drum and Fuser are combined with the toner hopper, so when the toner is depleted all the components have to be discarded.