UiiSii TWS21 Earphones

UiiSii TWS21 Earphones


My Rating



  • Good Customer Service
  • Good Bluetooth Connection


  • They Hurt
  • Microphone is Poor
  • Average Sound
  • Lags
  • Volume Control Don't Work

Today I’ll be writing about the UiiSii TWS21 Earphones, a true wireless set of stereo earphones. UiiSii have multiple audio products on the market.

It’s worth pointing out right now at the beginning of this review that this is my second pair of TWS21 earphones. The first pair was faulty, the left earphone was inoperable. In fairness to UiiSii they instantly sent out another pair without hesitation. These things happen!

The UiiSii TWS21 Earphones promise premium Hi-Fi quality sound, deep bass and 3D surround stereo. With built in CVC8.0 noise reduction design and a high-quality microphone. So should allow you to enjoy high fidelity music quality and clear calls too.

The UiiSii TWS21 Earphones provide up to 5 hours of Hi-Fi stereo sound or talk time on a single full charge (dependant on volume and other factors), and 20 extra hours in the compact charging case, which is powered by USB-C charging technology.

But are they any good? Sound Quality? Time to test them out!

Packaging and Contents.

The UiiSii TWS21 Earphones come packaged in a white cardboard box which features product images and specifications printed on it. The box measures 12.5cm x 12.5cm x 4.0cm and weighs 130G.

Image shows the outer packaging for the UiiSii TWS21 Earphones.
Packaging Image – Image Source – My Helpful Hints (Subject to Copyright)

Inside the box you’ll find the following: 1x Pair of Earphones, 1x Charging Box, 1x USB-C Cable, 1x Multi-Lingual User Guide.

Image shows the included contents.
Contents Image – Image Source – My Helpful Hints (Subject to Copyright)

UiiSii TWS21 Earphones.

The UiiSii TWS21 Earphones are white in colour and each earphone measures 3.0cm x 1.5cm x 1.5cm and weighs just 3G. Each earphone has a touch sensitive multi-function control area (more on this further down). The charging box measures 5.5cm x 4.0cm x 2.5cm and weighs 26G. Its pebble shaped and comfortable to hold and place in your pocket.

Image shows the UiiSii TWS21 Earphones Charging Box.
Charging Box Image – Image Source – My Helpful Hints (Subject to Copyright)

Inside the charging box is a 320Ah lithium-ion rechargeable battery. The charging box requires a prior charge using the supplied (or any) USB-C cable (which measures 18.0cm), charging takes around 2 hours and is indicated when the flashing LED light becomes a steady state light.

Charging Box.

You need to remove some insulating tape from each earphone prior to charging them. The earphones then can contact the charging box contact pins.

Image shows inside the charging box, there's the charging contacts.
Charging Box Image – Image Source – My Helpful Hints (Subject to Copyright)

The earphones magnetically attract to the charging case and make contact. It’s impossible to mix up the left and right charging contact points as the box is moulded for each earphone. To charge your earphones simply place them into the charging box, charging is indicated by the blinking LED lights on each earphone. It takes around 1.5 hours to fully charge these earphones, which will last around 3 hours (60% volume use). You should be able to get around 3 uses on a fully charged battery case.

Image shows the contact pins of the earphones.
Earphones Image – Image Source – My Helpful Hints (Subject to Copyright)


To pair you need to remove your fully charged earphones from the charging box. They’ll automatically go into pairing mode (indicated by flashing red and white LED lights), go to your device and perform a Bluetooth search for ‘UiiSii TWS21’ and confirm pairing. That’s it!

Every time you open the lid of the case, they automatically pair to the last know device, although on one occasion this didn’t happen for me, I had to do the whole initial pairing thingy again.

Image shows the connection method.
Product Image – Image Source – UiiSii (Subject to Copyright)

Wearing Them.

The UiiSii TWS21 Earphones go into your ear and you then slowly rotate them downward for them to fit both comfortably and securely. I found the plastic moulding of the earphone hurt my inner ear and after several hours my inner ear was seriously hurting, felt like they were being stretched, whilst being scraped with pen lid.

But they are incredibly lightweight, so at least I wasn’t in pain and feeling weighed down!

Product Image from UiiSii and shows the correct wearing method.
Product Image – Image Source – UiiSii (Subject to Copyright)

Improvements to the outer moulding would greatly improve the user wearing experience, certainly for me at least.

Multi-Function Uses.

The UiiSii TWS21 Earphones feature a touch sensitive multi-functional button control system, each earphone performs different function to provide you a handsfree experience.

They are advertised as being able to do the following:

  • Pause/Play: Press once on either earphone.
  • Previous Track: Press and hold for 2 seconds on the left earphone.
  • Skip a Track: Press and hold for 2 seconds on the right earphone.
  • Volume Decrease: Double tap the left earphone.
  • Volume Increase: Double tap the right earphone.
  • Siri/Google Assistant: Triple tap either earphone to activate.
  • Answer/End a Call: Short press either earphone.
  • Reject an Incoming Call: Press and hold for 1 second on either earphone.

All the above worked for me, except the volume control. It simply didn’t work, and I had to manually adjust the volume directly on my device, like some sort of pre-technological caveman.

Image shows the different function of the earphones.
Product Image – Image Source – UiiSii (Subject to Copyright)

Sound Quality.

The UiiSii TWS21 Earphones sound OK, that’s about it. They’re not the best, nor the worst I’ve tried out. Very middle of the road and meh!

On one occasion the sound was truly dreadful and sounded like I was listening to vinyl with crackles and pops. I put them back into the charging box and this seemed to resolve the issue.

Bass tones are present, but at the expense of vocals which sound muffled. The left earphone is slightly ahead of the right one, which is only noticeable at the beginning of each track, the left starts, then followed by the right.

There’s also a very noticeable lag when you watch video, the lips are around 1 seconds out of sync, which annoys me no end.

Sound is best set around 50/75% in volume, increasing to 90% volume level will leave you in agony as this is when audio falls off the cliff.

Sound cancellation is average, same with noise isolation. Nothing spectacular, everything average, or meh!

Image shows the earphones in my left hand.
Earphones Image – Image Source – My Helpful Hints (Subject to Copyright)

Bluetooth is advertised as capable of achieving a working distance of 15M. Tested this out and it’s true.

The built-in microphone is shite, and typical of the type of microphone setup you find in TWS earphones, well certainly budget ended TWS earphones. It’s alright to receive a quick call from some electricity switching scammers but wouldn’t be OK for Zoom calls or whatever you phone call loving people like to do.

Technical Specifications.

  • Brand: UiiSii
  • Model: TWS21 Earphones
  • Model Code: N/A
  • EAN: 6936608603562
  • ASIN: B08D3JLFT7
  • Charging Input 5V DC/ 2.1A
  • Bluetooth: Version 5.0
  • Bluetooth Range: 15M
  • Earphone Battery: 30mAh
  • Charging Case Battery: 320mAh
  • Earphone Charging Time: 1.5 Hours
  • Charging Case Charging Time: 2 Hours
  • Music Play Time: Around 3 Hours
  • Standby Time: 300 Hours
  • Speaker Size: 13mm
  • Frequency Range: 20-20KHz
  • Sensitivity: 96 ± 3dB
  • Impedance: 32Ω
  • Compliance: CE Marked, RoHS


The UiiSii TWS21 Earphones are mediocre at best. Sound is average, noise cancellation and isolation are average too. But they hurt to wear, the plastic moulding is shaped in such a way that it hurts the inside of your ear, it stretches and rubs against the skin of the inner ear.

First pair was faulty and top marks by UiiSii for instantly resending me another pair. That is a huge plus point, but the TWS21 earphones are not particularly good. A budget ended pair of earphones trying to be higher quality than they actually are.

Overall, would I recommend them? No, they aren’t for me!

If you want the UiiSii TWS21 Earphones for yourself, they’re available for purchase only on Amazon. The RRP for this product is £35.99.

Product sample provided by UiiSii in exchange for a detailed, unbiased review.

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