The CL 100 is an excellent amplified telephone with volume and tone control. It features: Adjustable receiving volume control up to 30 dB; adjustable receiving tone control +/- 10 dB; outgoing speech amplification +/- 4 dB; 3 emergency memories; 9 one touch memory buttons; big button keypad; last number redial; time break recall; mute; visual ring indicator; ringer button high/low/off; extra loud ringer up to 85 dB; and is wall mountable. It measures 20 cm x 10 cm x 21 cm and requires 4 x AAA alkaline batteries (not included).