A fuser kit is a component of a laser printer that does the actual printing. It consists of two rollers that the paper goes through. One roller is made of thick rubber to allow for pressure, while the other is made of thin metal so it can be heated up quickly. After the thin metal roller has toner on it, it heats up and presses against the paper and the thicker roller, transferring the toner to the paper. After a lot of use, your fuser kit may wear out and need a replacement. You can dispose of your old fuser kit in the garbage or you can recycle it.
