SM Pro Audio MBC502, Multi-Band Opto-Compressor 500-Series Module, Dual-channel multi-frequency-band optical compressor, 16-stage frequency range selector, Independent compression, attack time, and release time controls, Circuit bypass switch, Independent channel mutes, Master level display: VU meter w/ -20dBu - +3dBu range, Gain reduction LED display, Dual input gain controls, Master output level control, Housing: 500-Series Module