GM Microphones on September 19, 2015 | Marketing Team The GM-9 (9" length, 22cm) and GM-18 (18" length, 46 cm) gooseneck microphones feature a gold-plated, threaded, and locking 3-conductor quarter-inch phone plug connector. A fitted windscreen is included (not pictured). The uni-directional electret condenser mic element has a side and rear rejection of greater than 6 dB between 100 Hz and 10 kHz. GM-9 is compatible with I-Series and ICS Panels. GM-18 is compatible with Encore stations and ICS Panels (Other than ICS-1008E and 1016E).