These are new Bose Improved tactical headsets. These headsets are used in the US Military to protect users hearing. Also, they allow for communication while in loud vehicles. You can wear these headsets with or without a helmet. When worn with a helmet, the headset can be worn under the helmet or outside of it. This allows you to keep your helmet on while putting the headset on, or taking it off.
These are new style headsets; The Push To Talk has been upgraded and is more ergonomic.