Essentials for Beard Care! Minimize the appearance of gaps in your beard, mustache, or brows. Our long-lasting formula stays put all day without smudging or fading due to sweat... Designed with a four-pronged fork tip for a seamless appearance. Start by outlining your beard or mustache with the Beard filler pen and then fill in evenly for your desired shape. As you apply, use the soft-bristle BCOS brush to blend for a more natural finish.