Osamu retainer is a soft-hard contention appliance for a complete arch. A 1.5 mm flexible material (Ethylenvinylacetat) covers the vestibular and lingual teeth contour, the alveolar mucosa, leaving the occlusal surfaces uncovered. O 1.0 mm polycarbonate foil reinforces the entire structure. The double layer material offers increased comfort and durability, allowing the natural settling of the arches in occlusion.