The diameter of the open center of a loop coil in centimeters, specifically the inside edge of the tubing ring. This is where the wire path begins. The magnetic field concentrates between the inner and outer diameters. Used together with Loop Outer Diameter to describe the loop geometry. Measurements skip the wire zone between these two values.
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.
