All cartridges are tested one by one before delivery to ensure complete working condition perfect compatibility and excellent print quality. ???????????? ?????????? ?????? ?????????? ?????????? ???????????? ????????????????. Compatible Printers: HL-L6250DW Printer HL-L6400DW Printer HL-L6400DWT Printer MFC-L6750DW Printer MFC-L6900DW Printer Details of the Structure : This high yield black Drum Units the quality of prints clearly smoothly crisp dark sharp, keep real without fading, stably and long lasting. High-blackness Drum makes the picture delicate firm fixing, distinct layers and image high precision. Package: Shockproof packaging to avoid shipping damage. Every Drum Unit is under strict quality control, carefully inspected and packaged to ensure that it is in the best condition. Warm Tips : Avoid environments where temperature and humidity change rapidly, such as next to air conditioners or heaters. Store in a normal temperature and humidity environment. We always care about your needs, and we strive to provide you with high-quality and cost-effective products.