REL - R-528 - 500 Watt Subwoofer - Gloss Piano Black Type: Passive Radiator, front-firing active woofer, down-firing passive radiator ; Active Drive Unit Input Connectors: Hi Level Neutrik Speakon, Lo Level single phono, LFE phono ; Gain Control Range: 8 Fully Electronic with SET-SAFE: Yes ; D.C. Fault: Yes