Perfect Margin Shoulder Kit: PMS1, PMS2, PMS3, PM4 Tips, Universal Wrench and Metal Support (all autoclavable). PMS1: Preparation - shoulder shape with rounded internal angle. PMS2: Finishing - shoulder shape with rounded internal angle. PMS3: Polishing - shoulder shape with rounded internal angle. PM4: Corona-radicular preparation - conical shape. The shoulder shape of the instruments enables not only a better preparation of the cervical margin "lip", but also a finer finish inside the sulcus.