. This TN421M toner cartridge in magenta has been expertly designed to work seamlessly with your Brother printer providing you with highest quality results time after time. Though using cheaper non-branded cartridges might save you money in the short-term they’re not as compatible with your machine. It’s possible that using these often-inferior products could cause printing problems and even damage your printer – so why take the risk? By choosing a genuine TN421M toner cartridge you’ll ensure that your printer continues to perform at its very best and also that any warranty you hold remains valid providing you with extra peace of mind all round..