The KXTGM450S is a reliable and easy-to-use phone which improves many of the problem areas that those with hearing loss struggle with. Speech is louder with 50dB amplification, clearer with background noise reduction and tone control. Fast talkers are better understood with slow talk control while conversing in real time or listening to messages on the answering machine. The loud 112dB ringer with its bright red visual will always let you know when someone is calling! The (2) included KXTGMA45S expansion handsets have all the same features of the base phone and come with their own charging dock. Built-in battery back-up—a fully charged handset provides up to 13 hours talk time and 9 days standby. (2) Ni-MH rechargeable batteries AAA (R03) are included with base. With DECT 6.0 technology there is improved range and superior transmission between the base and handsets. You can expand with up to 3 more handsets for convenience in multiple rooms (see Accessories).