Sennheiser MX W1 Instruction Manual page 13

Press and hold the operation/pairing button of the
transmitter until the LED flashes rapidly.
ON
After approx. 3 seconds, the new earphones are also paired
to the transmitter. The LEDs flash blue once every 5 seconds.
ON
Note:
The distance between transmitter and earphones should not
exceed 1 m during association.
Associating the earphones to Kleer compatible devices
MX W1 is fully compatible to Kleer wireless standard. For pairing
the MX W1 with other Kleer compatible devices, please refer to
the preceding chapter and to the user manual of your device in
question.
7s
ON
ON
ON
ON
11