The Sharp AR-205 developer (often sold as AR-205SD or AR-205ND) is a black developer powder/component used in certain Sharp laser copiers. It’s a magnetic developer material that mixes with toner inside the printer’s developer system to properly charge and deliver toner to the drum, helping ensure consistent print density and quality. This is a separate consumable from the toner cartridge — machines with dual-component systems require both toner and developer.