The MXR Phase 90 M101 effects pedal virtually launched the phase craze.

The MXR M-101 Phase 90 Pedal provides classic phasing with variable speed control. Add shimmer to lead passages or jet-plane resonance to muted strumming. Not just for guitars, the MXR Phase 90 works well with bass, keyboards, and vocals. Vary the speed from a subtle, long cycle to a fast, watery warble with endless vintage vibrations in between. The MXR M-101 is powered by single 9V battery or Dunlop AC Adapter

• Effect Type: Phaser
• Technology: Analog
• Mono / Stereo: Mono In, Mono Out
• Controls: Speed
• Bypass Mode: Buffered Bypass
• Phase Effects Pedal for Guitar, Bass, and Keyboards
• Simple, single knob operation
• Wide range of sounds
• Works well with guitar, bass, keyboards, and vocals
• Knob varies speed from subtle to fast, watery warble
• Battery operation or with optional AC adapter