The MXR Custom Shop Phase 99 opens up the sonic palette of the iconic Phase 90 by combining two phase circuits into a single Phase 90-sized housing. Separate rate controls for each circuit allow you to create intense complex phasing, and a Vintage switch toggles between modern and vintage style phasing. Further, the Phase 99 features a P/S switch to toggle signal flow between the circuits from series to parallel, and a Sync switch to synchronize the rate of each phase circuit.