Bluetooth version: V5.4 Working frequency band: 2.402GHz -2.480GHz Power level: Power level 2 (Class II) Sound delay: Less than 20ms Power supply mode: built-in battery, 250mAh Charging interface: USB DC 5V type-c charging interface Applicable distance: 15M (no obstruction) Working current: Less than 20mA Working hours: 10H Usage environment: (-10℃--50℃) Audio input method: 1) 3.5MM audio interface 2) USB type-c interface Applicable equipment: Equipment with 3.5MM audio output and USB audio output functions, such as: TV, PC, MP3, CD and other equipment; Colour:Black Material:plastic Package Contents: 1 x Transmitter 1 x Receiver Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.