MXR says:

Go from crisp "bathroom" slap echoes to epic, Gilmouresque delays with the MXR Carbon Copy Analog Delay. Featuring 600ms of delay time with optional modulation, and a three-knob layout that controls Delay, Mix, and Regen. In addition, there are two internal trim pots that offer user-adjustable width and rate control of the modulation for even more tonal options. All done by a completely analog audio path for authentic rich, warm analog delay—made possible only by old-school analog bucket brigade technology. True bypass.