Custom Expression (Medium)

A3 Stompbox is a South Korean boutique pedal company known for hand-wired effects and custom volume/expression pedals built for professional musicians. The Custom Expression (Medium) provides smooth, reliable expression control for compatible effects pedals — a middle-size format that balances pedalboard footprint against comfortable foot travel. All A3 custom pedals are designed and hand-built to order with professional-grade components. Passive construction means no power required and no circuitry to fail. Single TRS output for plug-and-play compatibility with the broad range of effects pedals that accept external expression.