Through MB Quart, the pursuit of rich sound, while delivering deep bass impact, is what fuels Music. Defined. The all-new, Reference Series takes your audio experience to whole new levels of sound and clarity. The Reference Series will reward you with clear and high-end quality on all of your favorite tunes and playlists. High temperature adhesives are utilized to keep the coupling from cone to surround fused and are also impervious to cold weather. Molded Polymer Sealing gaskets are utilized to keep the speaker isolated from the mounting surface and improve protection from the water and dust intrusion. Red woven fiber cotton poly blend spider to stabilize the cone and voice coil in all musical situations. Venting allows air passage through the spider and speaker frame ribs to exchange air over the voice coil.