XM5, it does not have a physical dedicated on/off button it has a multipurpose where function is determined by how long you hold down the button. It’s not optimal design for me. I am sure a number of brands have moved towards this.

Second the sensor on the XM5 is known to be flaky. These are about a year old and already acting up.

It’s just a poorly built and poorly designed headset for me. I cannot even count the number of times I don’t notice they are on until the next day and they are dead.