Hands-free earpiece; turn on VOX function both at walkie-talkies and earpiece; walkie talkie earpiece with VOX; let you talk directly with your buddies Standard compatibility; upper pin 3.5mm; bottom pin 2.5mm; compatible with RT22 RT21 H-777 RT68 RT19 RT27 RT28 walkie talkies; etc Secret air earpiece; transparent tube is not easy to find; suitable for security; bodyguard at airport; club; concert; etc Stretchable length; the length of PTT to earplug can be stretched from 40 cm to 90 cm; ideal for team members of different heights One spare earplug which can be replaced simply and quickly; is coming with the package; earpieces provide more hygienic experience