The Leone expansion screws for removable orthodontic appliances derive from 80 years of extensive research, design and millions of clinical cases. The entire production process takes place in Italy with computer aided automated machines. The screws are made of bio-medical stainless steel of the highest quality and male screw threads with centesimal tolerances and total absence of surface roughness. The bodies and the guides are made with tolerances of +/-0.01 mm which ensure stability and precision. The wide range available allows the production of any type of removable device.