Features: 2.4G Wireless Broadcast Audio Transmitter Receiver; There are two options: built-in battery Transmitter & receiver and non-battery transmitter & receiver; The built-in battery transmitter & receiver can charge with type-c port; The battery-free version requires an external 5V power supply with Type-c port; It can be used in occasions requiring wireless audio transmission and DIY wireless speaker; 3.5mm sound port for input and output; Specifications: Material:Metal Color:Black Model:KCX_2.4G002 Size:Approx.6.5x4.7x2.4cm/2.56x1.85x0.94in Option Type:Audio Transmitter & Receiver with Buit-in Battery;Audio Transmitter & Receiver (No Battery); Working Voltage:3.5-5V Working Current:30-40mA Operating Range: Less Than 164 feet (Less Than 50meter accessibility) Transmit Delay:100mS Note: Please allow 1-2cm errors due to manual measurement,please make sure that you do not mind before you order. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Package includes: 1x2.4G Wireless Broadcast Audio Transmitter & Receiver