The AP-4 is a custom-designed interconnecting system that connects different audio processing systems like mixing consoles, digital signal processors, and other devices. It has two multi-pin connectors that are made with resilience in mind. It has been designed to be resistant to dust, dirt, and moisture. The connectors use a twist lock mechanism that helps locks them in place. As well as this, it is designed to operate in high frequency environments, meaning it is compatible with higher-sampling rate audio processing systems. The connections use a customized shield design, as well as a low-capacitance core, to reduce noise and distortion levels. The AP-4 can be used for both digital and analog audio systems.