Disassembled receiver unit illustrating the membrane shape and internal structure. The outer chassis dimensions are (7.9 × 4.1 × 2.8) mm³ in length, width and height, respectively. (Left) shows the back volume of the receiver with the coil, stack, armature and pin. (Right) shows the front volume with the membrane and suspension. The membrane area between the slits, we denote the membrane hinge.