True Wireless Earbuds

Sounds like an oxymoron as Bluetooth is wireless by design.
Normally a wireless headset has a Bluetooth receiver and a DAC/amp driving the speakers. You need a wired connection between both speakers and amp.

You can get in-ears without the connecting wire.

To distinquish them from the "normal" wireless models, they are called True wireless earbuds.

 

Generally speaking, true wireless earbuds have a primary – or master – earbud which acts as a bridge between the audio source and the secondary earbud. In addition to managing the connection between the two earbuds and the audio source, the primary earbud works to compensate for any audio delay – also known as latency – that can occur between earbuds during transmission.

To reduce latency, the two earbuds send information between themselves and calculate how long this process takes. Once this timeframe has been calculated, the earbuds understand how long the process should take which allows the master bud to compensate for any latency and ensures the earbuds remain synced to each other and to the source device. It’s important to note that latency can be strongly affected by environment, such as crowded or built-up areas, which can cause brief interruptions while listening to music or having a conversation.

Panasonic

 

TWE

Today, thanks to Bluetooth 5 and its multipoint connectivity, instead of a master handling the Bluetooth and passing the L channel to the slave, both connect directly to the phone.

This improves the stability of the connection.

 

CrazyBaby Air US$ 159

A true wireless Bluetootth headphone.

 

Added 2016

Earin M-1 $199

 

Added 2017

Hearable Lab FlapFit

 

Added 2018

Motorola VerveOnes+ 249.99

Added 2016

Samsung Gear IconX €200

Fitness tracker with 4Gb memory

Hold 1000 songs max.

Added 2017

 

The Best True Wireless Headphones So Far - The wirecutter ( July 2017)

What are True Wireless Earphones and How do They Work? - Panasonic (2021)

Why is true wireless connectivity so bad? - SoundGuys (2021)