Base for lingual positioning of clamping screws Quadra is a model holder base which allows a wide range of positioning of the insertion axis and of the rotation axis of the model. Specifically designed for such works that need milling, drilling and threading on axis with wide divergence as for example by lingual positioning of the clamping screws of superstructures on implants. The model holder Quadra inclinable shelf allows the variation of the models insertion axis from the original position up to the angle at a distance of 135° from it. The combination of this movement with that of the rotation of the goniometric support on the 360°angle, allows any inclination or desired position tobe reached, giving the possibility to go back to the starting position at anytime. The model holder Quadra goniometers are marked with reference lines, engraved following a 10° arithmetical progression, allowing in this way an approximate evaluation of the inclination and rotation values. The picture shows Quadra base with assembled the model holder plate A54/P, accessory not included.