The EMG 81 is a popular active humbucker guitar pickup manufactured by EMG, Inc.. It is usually considered a lead pickup for use in bridge position, paired with EMG 85 as a rhythm pickup in neck position (Zakk Wylde is famous for this configuration). It's not uncommon, however, to see a guitar with two EMG 81s in both bridge and neck positions (for instance, Kirk Hammett's EMG-KH21 pickup sets, which include 2 EMG 81 pickups for both neck and bridge positions).