In the words of Fairfield Circuitry:

A simple dual TRS (stereo) to TS 1/8″ breakout, giving your modular and semi modular gear easy access to TRS CV jacks, such as the one on Randy’s Revenge, greatly expanding it’s capabilities.

You can also hijack the EXP inputs of many popular pedals, giving you a solid 5V on the ring (assuming wiper-to-tip standard) and CV in on the tip.