The Ohm M was the satellite part of Ohm’s first sub-woofer/satellite system as introduced in the mid 1970s. It had a metal cabinet, 4” woofer/mid-range and 1” dome tweeter. It was vented to increase the output headroom and had a built-in high pass filter. The sound of the system with the sub-woofer matched the high end Ohms but took up a tiny fraction of the space.