The HMEC 461 headset from Sennheiser is designed primarily for private pilots operating propeller and turboprop aircraft. It features the same sound quality as the HMEC 460 and introduces powerful connectivity options. Designed for battery operation, it has a lightweight control unit that allows pilots to activate NoiseGard, as well as the ability to select a stereo or mono signal or independently adjust right and left volume controls. Pilots can also connect a mobile phone or an audio source to the unit; any time a radio signal is received, the audio source is automatically interrupted and the ATC signal is transmitted. NoiseGard technology reduces high-level continuous noise by about 90% in the cockpit.