Brother LEK243001 Ink Absorber Box is a printer maintenance part that collects ink produced during print-head cleaning. Brother identifies this part number as an ink absorber box, and its user guide explains the box’s role in containing that cleaning ink.
The listed compatible models are MFC-J3520DW, MFC-J3720DW, MFC-J6520DW, MFC-J6720DW and MFC-J6920DW. This replacement part is intended for the absorber-box position in those printers. The parts documentation lists one box under code LEK243001.