Remote Speaker Microphone without Audio Jack (IP57). The RSM incorporates both wind porting technology and waterproof capability. The IP57 submersible RSM is tested at 1 meter for 30 minutes which is ideal for outdoor radio communication in wet conditions. Motorola OEM PMMN4027, PMMN4027A IP57 Submersible Remote Speaker Microphone with Windporting Technology PTT Mic Compatible with Motorola radio models: GP140, GP240, GP280, GP328, GP330, GP340, GP360, GP380, GP540, GP580, GP640, GP680, GP1280, HT750, HT1250, HT1250LS, HT1550, HT1550XLS, MT Series: MT850, MT850LS, MT950, MT8250, MT8250LS, MT9250, PRO860, PRO5350, PRO5450, PRO5460, PRO5550, PRO5750, PRO7150, PRO7350, PRO7450, PRO7550, PRO7750, PRO9150, PTX700, PTX760, PTX780, MTX950 MTX 950, MTX960 MTX 960, MTX8250 MTX 8250 MTX8250LS MTX 8250LS, MTX9250 MTX9250