The Epson S051201 photoconductor unit does the majority of the yellow toner distribution for the toner cartridge available separately. This genuine Epson C13S051201 offers you the very greatest print quality for your Epson AcuLaser C3900TN.When the print quality produced by your old Epson S051201 begins to deteriorate, look no further than this original photoconductor unit. Installing a brand new Epson C13S051201 photoconductor instantly brings the prints of your printer back up to Epson standards.