Starter BROTHER TN-339-series cartridges require that a flag gear be installed to function after being refilled.
In Stock
If the cartridge that you are trying to refill was the original cartridge shipped with your printer, you will need to purchase this product because such a cartridge will not already have a flag gear installed.
You will need one flag gear per starter cartridge.
Flag gears are also available in a pack of 4.
Each Flag Gear Kit contains the following: