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  • Writer's pictureYewge

Ko-Star KTW-20 (K20) TWS Bluetooth Earphone Review

Updated: Aug 3, 2020

The Ko-star KTW-20 (also known as K20) Bluetooth Earphone could be widely used on various devices and daily activities. The ergonomic design ensures that the earphones sits comfortably on your ear while you are working on your job, commuting and jogging. Whether you are an iPhone or Android user, the K20 will work equally well.

Key Highlights

Bluetooth 5.0

The Bluetooth 5.0 technology offers faster pairing with another device, lower power consumption and quicker transmission of sound.

Automatic Pairing

After your first pairing of the earphones, the earphones will be automatically connected to your phone once it is taken out of the charging case. Make sure your bluetooth is turned on before that!


The portable charging case comes with a 500mAh battery and each earphone with a 45mAh Li-ion battery. The publicity poster indicated that the working time for each use will be up to 3 hours, and extra 15 hours with charging case. That's 18 hours in total.

Go ahead and conveniently recharge the earphones anytime and anywhere. Don't forget the charge the charging case though! Batteries in the charging case can be recharged with a Micro USB cable.

Magnetic Case

The slots for the earbuds in the portable charging case will securely contain the earbuds with magnets. Not to worry, your earbuds will not drop out of the case even if you flip it around. The magnets are strong enough to keep the earbuds in place, but they ain't that strong, so you do not have to worry about having a hard time removing the earbuds as well.


The earphones comes with an IPX5 waterproof rating, which is resistant to water sprays from low pressure jets. The earphones will be fine as long as you do not soak them into water.

Built-in Microphone

Whether you are a gamer sitting in front of your computer, driving a vehicle, or doing your routine jogging, the built-in microphone enables you to pick up the phone with the press of the button and speak as though you are talking to yourself.


The pocket sized overall K20 dimensions are about 7.9cm in length, 4cm in breath, 3.8cm in height, and weigh about 50 grams.

Note: Please allow measurements error of 1 to 3mm due to manual measurements.

Supported Bluetooth Profiles


Touch Control Functions

Our Test

Audio Performance

We were impressed by the deep bass on the K20 wireless earphones and clear stereo effects, rendering a more enjoyable experience.

Battery Performance

Before beginning, the batteries will be recharged till it is 100%. Then, we will start using it from 100% to 0% while logging our usage down.

The LED indicator at the center will blink while it was being recharged with the Micro USB cable. If the earphones are already fully recharged, all the 4 LEDs on the indicator will light up and stop blinking.

Red LED on the earphones will light up during charging, and turn off after it has been fully recharged. Once the charging case hits 0% battery, the first LED on the left of the indicator will blink rapidly before switching off by itself.

The portable charging case was able to recharge the earphones four times, and it was able to recharge the earphone till 80% on the fifth time before running out of battery. Each use lasted about 3 hours, and the last 80% managed to play music for 2 hours 26 minutes. This meant that you could use this device for at least 18 hours if you have fully charged both the earphones and charging case before using.

Before the battery runs out and automatically disconnects, a "battery low" warning will be played only once, to inform you that it's time to let your ears take a break. The earphones will be turned off shortly after.

Did it really last 18 hours?

On average, each cycle could last about 3 hours with non-stop playing of music. Recharging the earphones to 100% again with the charging case took slightly more than an hour.

In total, the usage duration was slightly more than 18 hours, matching the specified running hours. Effectively, this is enough to last you a whole day or two to three days if you are not a heavy user.

Usage duration observed

  1. 3 Hours 20 Minutes

  2. 2 Hours 58 Minutes

  3. 3 Hours 09 Minutes

  4. 3 Hours 14 Minutes

  5. 3 Hours 14 Minutes

  6. 2 Hours 26 Minutes

Recharging duration observed

  1. 1 Hour 7 Minutes

  2. 1 Hour 6 Minutes

  3. 1 Hour 11 Minutes

  4. 1 Hour 10 Minutes

  5. 54 Minutes

USB charging duration from 0% to 100%

  1. 1 Hours 59 Minutes


We actually enjoyed using the Ko-star K20 for the bass it offers, and did not feel any kind of discomfort when using this product. If the size of the ear tips did not fit your ears, you could refit it with the smaller sized ear tips provided with the package.

Whom is this for?

If you are looking for a set of wireless earphones that offers deep bass and clear music, this is for you. However, the audio quality comes at a price.

Where to buy?

The Ko-star K20 Bluetooth Wireless Earphone is available at our online retail store. Get this from us today!

In the Package

  • 1 piece K20 Bluetooth Earphone and Charging Case

  • 1 piece 0.25m Micro USB Charging Cable

  • 1 pair of silicone ear tips

What do you think?

Leave a comment below to share your views!

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