The innermost region of the magnetic field where strength is above 75% of peak. This represents the most concentrated portion of the field output, the strongest part of the field the accessory produces. For a pancake coil, this zone is centered. For a donut coil, it follows the ring pattern of the coil.
Also known as: High-Intensity Flux
Concentration score asks how much of the field lands in its strongest zone. The gauge on the left is that score as a percentage, the same gauge the report shows. On the right is the field it measures: the core is the region at or above half the peak strength, and the score is the share of the field inside it. A tightly focused coil puts most of its field in the core and scores high; a broad coil spreads it out and scores lower. It describes focus at the surface, not depth.
