**********Work straight out of the box; compatible with RT15 RT18 RT19 RT21 RT22 RT27 RT28 walkie talkies*****Solid build portable 2 way radios; easy to operate and use; signal prompts let you know the receiving and sending status of the radio; channel display; you can clearly see the current channel*****Clear sound ensures more effective communications between team members; 0-9 levels squelch and secure call give you and team more secure; emergency alarm gives you another layer of protection at work*****Quality accessories included; 2 Pin acoustic tube headset can ensure clear sound in noisy environment; ergonomically designed belt clip with extra durability; dual USB port chargers make charging faster and than ever*****Achieves transmission activated by your voice, no need to press PTT to talk, very convenient especially when you are busy