The overall outer diameter of the accessory enclosure or pad in centimeters. This is the physical size you'd measure with a ruler. It serves as the boundary for field coverage analysis, heatmap scaling, and effective area calculations. For loops, this refers to the outer edge of the tubing ring, not the inner opening.
A PEMF accessory takes a few physical forms, and the form sets how the field is laid out. A disc concentrates the field in a spot, a paddle puts that disc on a handle, a loop is a ring that surrounds a limb, and a mat spreads many coils across a wide surface. A loop is described by two diameters: the inner diameter of its open center and the outer diameter of the whole ring.
