Battery operated in-line amplifier to increase the audio level in the earpiece of the telephone handset by 30dB - over 10 times the normal volume. Very good for users with a mild hearing loss that want to continue to use a standard phone. The T-Loud switches on and off automatically when the telephone handset is lifted and replaced.T-Loud In Line Telephone AmplifierAmplify Your Existing TelephoneT-Loud is supplied with a battery connection lead and full user instructions. Please note: this product can only be used with standard wired telephones with a detachable handset with RJ10 (small 10mm square) connectors.