The ICOM HM-231 is a waterproof aviation speaker microphone designed for use with the Icom IC-A25 series handheld airband transceivers. It is built for cockpit, ramp, and outdoor aviation operations where reliable audio and hands-free radio operation are required in wet or harsh environments.

The unit combines a high-output speaker and a push-to-talk (PTT) microphone in a rugged, sealed housing rated to IP67, allowing temporary immersion and full dust protection. It connects via Icom’s 2-pin slim L-type aviation connector and includes a flexible coiled cable for mobility in cockpit use.

This model is the official OEM accessory for the IC-A25C and IC-A25N radios and is intended for professional aviation communication workflows including flight training, ground handling, and general aviation operations.

Key features include:

Waterproof construction (IP67 rated, dust-tight and immersion resistant) 
Compatible with Icom IC-A25C, IC-A25N, and IC-A25NE radios 
2-pin slim L-type aviation connector system 
Coiled cable (~500 mm / 19.7 in retracted length) 
Lightweight handheld design (~115 g) 
Integrated speaker + PTT microphone in one unit
Ruggedized housing for aviation and outdoor use
8-position rotating belt clip for flexible mounting 
Optimized audio clarity for noisy environments (cockpit / ramp)
OEM accessory designed for Icom airband handheld ecosystem