... diagnostic function.Aesthetic and endurable battery handle is equipped also.WG-I,II,IIB,Diopter compensation: ±1,±2,±3,±4,± ... 5,±6,±8,±10,±12,±15,±20,-25,-30WG-III,Diopter compensation: ±1,±2,±3,±4,±6 ... ,±8,±10,±15,±20,±25,+40WG-IIIE,Diopter compensation: ±1,±2,±3,±4,±5,± ... ±1,±2,±3,±4,±5,±6,±8,±10,±15,±20,±25,+40Although ear specula's diameter varies,it still can be ...