TCL Over-Ear Bluetooth Headset, HRA, slim fold, Frequency of response: 9-40K, Sensitivity: 100 dB, Driver Size: 40mm, Impedence: 24 Ohm, Acoustic system: closed, Max power input: 50mW, Bluetooth (BT 5.0) & 3.5mm jack, Hi-Res Audio,Color Cement Gray