Is your beard longer than 9mm and do you want to trim it shorter? We recommend one of these beard trimmers for a long beard. That's useful if you want to grow your beard, but like to trim it sometimes. The most accurate way to tame your beard growth is with a comb attachment. Usually, it's an adjustable comb attachment with various shaving lengths. Or, individual comb attachments with different lengths that you click onto the trimmer separately.