For music lovers who demand only the best, HDX and HDS10X speakers are powerful with coated drivers that are tuned to deliver true fidelity and tight powerful bass. You don't buy HDX to fit your helmet, you buy your helmet to fit HDX - that's how good they are. For the best performance, use with UCLEAR Bluetooth controllers with CLEARLink mobile app and graphic EQ (best settings for graphic EQ are "6" for treble, "9" for mids, and "6" for bass). Premium HDX coated drivers. Gold-plated 3.5 mm jack. 4.5" speaker to jack, plus 3' extension cable. 47 mm OD; 42.5 mm driver. 100dB/m ±3dB sensitivity. Impedance 32 ohms. See also HDS10X (P/N 111046) if you need a smaller speaker that still rocks! Compatibility with UCLEAR MOTION Series requires adapter (P/N 111044, 3.5mm Speaker Adapter For Motion Series).