This speaker microphone has a Push To Talk (PTT) key and has a “Hung-up switch” that act as the “hook” switch (without the need to provide a vehicle earth to the hang up clip). A RJ45 connector on the microphone lead plugs into the radio’s front panel. This connection is protected by a snug fitting rubber boot designed to keep the connections free from dirt and moisture, and preserve the IP54 and other environmental protection specifications. The microphone has been designed for maximum durability. It contains impermeable silicon treated membranes which eliminate corrosion problems caused by moisture. It also has a sealed microphone switch to protect against corrosion.

Whilst the microphone may look similar to the GM300 microphone, on which it is based, it is in fact considerably modified to provide an enhanced audio performance. This microphone is suitable for the following Motorola mobile radios - CDM750, CDM1250, CDM1550, CDM1550-LS, CDM1550LS Plus, CM140, CM160, CM200, CM300, CM340, CM360, DeskTrac, EM200, EM400, GM1100, GM1200, GM1280, GM140, GM160, GM2000, GM300, GM3188, GM338, GM340, GM350, GM360, GM3688, GM380, GM600, GM640, GM640, GM660, GM900, GM950, GR1125, GR1225, GR300, GR400, GR500, GTX Mobile, LCS2000, LTS2000, M10, M100, M120, M1225, M130, M200, M400, MaraTrac, MaxTrac, MC2100, MC900, MCS2000, MCX1200, MCX2000, MCX600, MCX760, MCX780, PM400, PRO3100, PRO5100, PRO7100, SM120, SM50, Sportbase, etc. If you are going to use this microphone with radio amateur equipment, it's easy to modify it for Icom transceivers with better results than you can get with original Icom microphones. The microphone comes with the hang up mounting clip.