This is a new unused Black Extra High Yield Return Toner Cartridge for the CS 510 Laser Printer. I bought this in error for my CS 517 printer. When I installed it, the printer would not accept it. My owners manual stated this was correct for the 510 series but that was in error. I had to buy another cartridge specifically for the CS 517. My return date to the seller had passed and it is offered to you at a discounted price.