^_^ Premium toner cartridge e-studio 205L 255 305 355 455 for Toshiba Guarantee: All products go through as following professional test before delivery 1). Mechanical test to ensure the toners smooth operation and no noise, and to meet with ISO standards. 2). Environment protection test to ensure toners' environmental safe. 3). Duration test to ensure toners can last more than one year. 4). Difficult conditions tests such as abnormal temperature, air pressure, strong sun light and rough transportations tests to ensure the printing quality remains high. 5). Water resistant test to ensure printing won't fade and be diluted when wet. 6). Printing quality test to ensure the printing is real black, no slur and won't fade. 7). Capacity test to ensure the print volume is the same as the ones of original manufacturers