M9A is a NiZn ferrite with an initial permeability (μi) of approx. 50, a saturation flux density (Bs) of approx. 340 mT at 25 °C (300 mT at 100 °C) and a Curie temperature above 300 °C. It shows excellent Q across 5–50 MHz (loss factor 100×10⁻⁶ at 5 MHz / 120×10⁻⁶ at 20 MHz) while keeping Bs at 340 mT with 300 mT still available at 100 °C — one of the few high-frequency grades combining high Q with real flux capability, suited to RF magnetics that must carry power. Typical uses are shortwave/mid-frequency RF filters, power-stage RF chokes and tuning inductors. In the ladder it sits between V2F1 (μi approx. 30) and M61 (approx. 100): a lower ceiling than V2F1 but higher than M61, and its balance of power handling and Q makes it the workhorse for HF power RF.