Sony WF-1000XM4 True Wireless Replacement Earbud Black OEM-Right (version 2.0.1)
only right side 

Initializing the headset to restore factory settings

If the headset does not operate correctly even after resetting, initialize the headset.

Place the headset in the charging case, leave the lid of the charging case open and wait for lights to flash repeatedly (red) in sets of 3, then hold your fingers to the touch sensors on both the left and right units for about 10 seconds. Release your fingers when the indicators (red) of the headset start flashing red at a slower pace.

The indicators (green) flash 4 times (     ), and the headset is initialized. This operation resets the headset to the factory settings and deletes all pairing information. In this case, delete the pairing information for the headset from the device and then pair them again.

If the headset does not operate correctly even after initializing, consult your nearest Sony dealer.