The clarity ha-40 portable telephone handset amplifier makes telephone conversations not only louder so they are clearer and much more easy to understand. The ha-40 increasesing call volume up to 40db and features a boost button which eliminates background noise and feedback. The ha-40 amplifierpatible with most home and office telephones with modular handset cords. Clarity has been offering life changing solutions for over 40 years. With better performance and more advanced technology, claritymunication solutions to help you maintain an independent, secure, and engaged lifestyle. The truth is, not all amplified phones are the same. There is more to a good amplified phone than loudness, just as there is more to a car than how fast it can go. There are many elements that are required to create quality audio for clear conversation. Each clarity phone contains patented technology to suit your hearing needs, giving you the best telephone experience possible. Ha 40 features: in line amplifier designed for people with mild to severe hearing loss adjustable amplification up to 40 db tone compatible with most home and office telephones connects easily between corded handset and phone basebattery include