Solar tts specification: - bluetooth v2.0 - supports bluetooth hsp/hfp/opp and at command - talk time / standby time: 10 hrs. / 250hrs. - multi-language tts system (us english, uk english, spanish, french, dutch, chinese) - bright led indicator for working status - speed dialing - bluetooth link auto connection - full duplex with noise and echo cancellation (dsp) - microphone gain control - digital volume control - able to recognize up to 4 paired units - no installation required - built-in battery 20x12x7cm.Weight:0.5kg