1 Pin 2.5mm; compatible with Retevis RB48 RB48 Plus RB48A RB48 Pro RT49 RT49B RT49P 2 way radio; don't compatible with DEWALT, Gaswei G2pro walkie-talkie Two-way radio earpiece with side PTT and microphone; implement one-click call Detachable transparent tube make clean more easy Use transparent tube design; it can be hidden well and make your calls more private Strong cable; the diameter of cable is about 2mm; thick cables will last longer Retevis RB48 RB48 Plus RB48 Pro walkie talkie earpiece