The Novo M3 hearing aids are traditional "Behind-The-Ear" (BTE) open conduction (ear tube) devices and utilize the latest in digital signal processing technology to bring you clear sound free of background noise in a small and fuss-free design. Some of our customers have been requesting the option of having single side devices so we have made that possible with the M3. The phenomenon known as "Binaural Summation" refers to fact that sound is perceived to be 3dB-6dB louder if heard in two ears instead of one. So if possible, we suggest that you consider using two devices in order to benefit from better hearing.