The Type-51 Directed Energy Rifle/Improved (T51 DER/I), more commonly known as a Plasma Repeater, is a plasma-based Directed Energy Weapon used by what used to be the Covenant Empire, specifically the Sangheili and Jiralhanae, during the Fall of Reach in August 2552. The weapon also saw action in the post-war years in the hands of Jul 'Mdama's Covenant.