Specifications
Model: KN321 or KN319
Technologies: KN321:BT5.0,KN319:BT4.2, A2DP, AVRCP (receiver mode only)
Operation Range: Up to 10m / 33ft (without any blocking objects)
Pairing name:KN321/KN319
Charging Time: 2 hours
Working Time: RX:6 hours ; TX:5 hours
Battery Type: Li-Polymer (200mAh)

Dimensions: 44 × 44 × 12mm 
Weight: 18g

Package Content
1x Bluetooth 5.0/4.2 Audio Transmitter/Receiver Adapter
1x Micro USB Power Cable
1x RCA Cable
1x 3.5mm Aux Cable
1x User Manual

Features:
1.This extremely portable, lightweight wireless audio transmitter & receiver is an ideal wireless audio solution for a wide range of situations and uses

2.Transmitter mode:wirelessly streams audio from your non-Bluetooth TV, home stereo system, or CD player to your Bluetooth headphones or speakers

3.Receiver mode: wirelessly streams audio from your Bluetooth-enabled phone, tablet, or computer to your wired stereo, speakers, or headphones

4.Switch between transmitter and receiver modes with the simple flick of a switch. Effortlessly connect using advanced Bluetooth technology and 3.5mm audio cable (included).

5.Super-Portable Audio-Streaming Power
The KN321 is just 44mm (1.73") across and weighs only 18g (0.63oz),but has got powerful wireless audio streaming capabilities. Slip this transmitter & receiver into your backpack or laptop bag and take it on-the-go without the slightest effort.

6.Broad Compatibility: With the included 3.5mm cable and 3.5mm to 2RCA cable, this Receiver Transmitter adapter can widely be used on your computer, laptop, home stereo system, headphone, smartphone, Mp3 player, CD player, etc.

Power on: Press and hold the power on/off button until the LED lights up

Shutdown: Press and hold the power on/off button until the LED is off 

Charging: Use the DC-5V charger and micro usb charging cable. The red light is on during charging. When the battery is fully charged, the blue light is on.

Switch mode:
1)RX: Receive mode, indicator: blue LED
2)TX: Transmit mode, indicator light: red LED

RX mode:

Pairing name: KN321/KN319, find KN321/KN319 in the Bluetooth settings of the phone to pair. The blue light flashes twice a second during the pairing process, and the blue light flashes once every three seconds after the pairing is successful. 
how to use:
1)Plug one end of the audio cable into the audio input of the speaker and the other end into the audio of the KN321
2)confirm that it is in RX mode (blue light flash). Find the pairing name in the Bluetooth settings of the phone: KN321/KN319 click to pair.

TX mode: 

TX mode will automatically search for other Bluetooth receiving devices (such as Bluetooth headset, Bluetooth speaker, Bluetooth receiver, etc.),The red light flashes twice a second during the pairing process, and the red light flashes once every three seconds after the pairing is successful. 

How to use: 
1)Plug one end of the audio cable into the audio output of the devices and the other end into the audio of the KN321/KN319.
2)Confirm that it is in TX mode (red light flash). The KN321 will automatically search for Bluetooth headset or Bluetooth speaker pairing.