MXR got the phaser right in 1975 with the Phase 90, even though its circuit design was inherited by Whirlwind’s 1973 effect. That was the first pedal sold by the company and – to date – still one of the most popular. Two years later MXR released the Phase 45, a mellower version that works better for clean sounds.
Recently the company introduced the Phase 95, which offers both circuits in a single, mini pedal that’s about half the size of the original models – so you get twice as much with half the footprint!
More about its controlsdierctly from the manufacturer’s webpage:
The 45/90 switch toggles between the Phase 45 mode’s subtle two-stage phasing and the Phase 90 mode’s more pronounced four-stage phasing, while the Script switch toggles between two phasing styles. The Phase 95 is set to modern style phasing by default, which relies on feedback to create light harmonic distortion and gives the effect a more accentuated swoosh. Engaging the Script switch removes feedback for a lusher, more subdued sound with higher headroom and greater clarity. The familiar Speed control sets the rate of the effect.
Here are a couple of recent videos of the MXR 95, you can find more info here.