Features All-Passive tone sculpting circuitry Unique Shelf curves use the "bandwidth" control Overlapping and Interleaved Frequency choices Every band switchable to shelf or bell Vacuum tube make-up gain and line drivers Description Product Description Includes 1 Year Free Extended Warranty. This is the Mastering Version of the Massive Passive with innovative repeatable, mechanically detented knobs of our own design. Range is clamped down for focus where mastering engineers live and breathe. Filters go higher and lower for solving problems in the mastering stage. FEATURES: All-Passive tone sculpting circuitry Unique Shelf curves use the "bandwidth" control Overlapping and Interleaved Frequency choices Every band switchable to shelf or bell Vacuum tube make-up gain and line drivers Parallel symmetrical topology Premium components throughout HP and LP Filters plus gain trims Metal Manley mechanically detented GAIN and BANDWIDTH control knobs