Review on Efficient Replacement: F-INK Empty Refillable Ink Cartridge for Brother LC201 LC203 LC203XL, Compatible with Brother MFC-J4320DW J4420DW J4620DW J5520DW J5620DW J5720DW Printers by Curtis Kincade

I bought these over a year ago thinking I might need them sooner. I just installed 2 today, no problem. Thank God the printer recognized them immediately. They work great. I just don't know what those tiny black bits in the cartridge packaging are for, but obviously I don't need them, but I'd still like to know what they're for. UPDATE: July 2021, cartridges completely stop working. POOH! NOT HAPPY NOW! WHY DID YOU STOP WORKING? I HAVE TONS OF INK I CAN'T USE!