Yaesu MH-73A4B Submersible Speaker / Microphone Specification:

• Submersible IPX7 (1 meter for 30 minutes)
• Mic Element: Electret Condenser
• Mic Impendance – 680 Ohm or less
• Speaker Impedance – 4 Ohm
• Output Sound Pressure Level – 81.5 dB ± 2dB/W (1 m)
• Rated Input – 0.5W
• Maximum Input – 1.0W
• Dimensions (W x H x D) – 2.4″ x 3.3″ x 1.5″ 60 x 85 x 37.5 mm
• Weight – 5.3 oz (150 g)