The Plantronics MHA100 Mobile Headset Amplifier amplifies incoming sounds up to 24dB and makes words easier to understand with Clarity® Power™ technology. Clarity® Power™ technology increases the volume of high frequency sounds, the kind of sounds many people can't hear clearly on the phone. Discreet, portable and convenient, the MHA100 can be used in any environment when a standard mobile or cordless phone may not provide enough volume. It is also the ideal solution for those who experience mild to moderate hearing loss. The MHA100 may be used with most mobile and cordless phones which utilize a 2.5mm headset jack.