: Some versions feature a removable security faceplate. To attach it, set the right side into the bracket first, then press the left side until it locks.
Based on standard Clarion OEM units of this series, the PX-3994A-A typically includes: Audio Sources Clarion Px-3994a-a Manual
If you are installing the Px-3994a-a yourself, keep these critical safety points in mind: Clarion | Product Manuals Download Service : Some versions feature a removable security faceplate