Creative Sound Blaster SB1521 Audio Control Module Volume controller unit only. For Creative sound cards. This is the Audio Control Module (ACM), model SB1521. It's a convenient controller that allows you to switch between headphones/microphones and adjust the volume at your fingertips. Audio Control Module (ACM): 3.5mm microphone input (mono) x1 6.3mm microphone input (mono) x1 3.5mm headphone output (3-pole) x1 6.3mm headphone output (3-pole) x1 Cable length: Approximately 1.4m