Clarity W10 AC-powered in-line receiver amplifier W10-00 allows the user to amplify the receiver volume 3 times higher than normal (up to 20dB) using their current unamplified handset. W10 Features & Benefits: The W10 easily installs between the existing telephone base and the current handset, and improves listening volume up to 20 dB for clearer reception. It uses a rotary (thumb wheel) volume control to adjust to individual hearing needs. Includes a AC power supply. Portable for travel and is compatible with electronic or standard phones. (The dial pad must be in the base of the phone.) Perfect for the hearing impaired. The W10 series boost the receiver volume over three times the normal level, making hard-to-hear calls easier to hear. Amplifier Gain: + 24dB Frequency Response: Flat within +/? 5dB from 300 Hz to 3000Hz W10 Color: Black