Active speaker pair with a front-facing 3.5 mm input and headphone jack. All monitors in the Eris series feature special Kevlar-cone woofers. The unique weave and material properties of the 4.5" Kevlar woofers in the Eris 4.5 ensure a more uniform dispersion across the entire frequency spectrum, which helps to eliminate timing errors in audio playback and results in a clear overall sound.