The Brother LC223 LC225 LC227 refillable cartridges have been shipping with small black plastic pieces. In the vast majority of cases these will not be needed, but are included with the package to cover all of the bases. There are two different kinds of original Brother LC 223/225/227, and a small percentage of cartridges use a slightly different shape cartridge, and the small black plastic pieces fit onto the refillable cartridges to contact with the printer sensor.
Below are fitting instructions. They show how and where to remove and replace the plastic sensor piece.
LARGE RHINOFILL REFILLABLE PRINTER CARTRIDGES + 400ML INK BROTHER LC223 LC 223
NORMAL SIZE REFILLABLE PRINTER CARTRIDGES + 400ML INK BROTHER LC223 LC 223 Non OEM
All brand names and trademarks are the property of their owners and are used for descriptive purposes only. The above products are Non OEM (Not made by Brother).