This product features a 5.2 Bluetooth TWS case matching function. It supports 5W x 2 speakers and 3.5mm AUX input. Hands-free calling is supported, along with 3-port output. Operating voltage is 5V; current is 2A. After secondary development of peripheral hardware, maximum output power can be configured up to 5W. The Bluetooth device name is ymx-878bt. Power supply requirements: DC input voltage 3.7–5V, current 2A–3A or higher. The USB socket is for charging input. When charging, the red LED lights up; when fully charged, the red LED turns off. Use a lithium battery with a protection board. For TWS functionality, two Bluetooth modules are required. To activate TWS, briefly touch the key signal pin to ground (GND) using a switch or wire—this enables mutual pairing. Note: this is a momentary touch, not a continuous short circuit. A single module supports standard Bluetooth functionality. When TWS is connected, audio output is mono; when TWS is disconnected, output is stereo. Color: As shown in image Material: PC + Metal Package Contents: 1 x Power Amplifier Board Note: Other items not included. Light reflection and differences in display screens may cause slight variations in color between the image and the actual product. Measurement tolerance: ±1–3 cm.