T Twin Blocks is a functional appliance with modification of the occlusal inclinedplane, this device consist of upper and lower bite blocks that interlock at a 70degree angle, engage on occlusal inclined plane. This appliance is effectivefor correcting the skeletal class II malocclusion. Twin Blocks are designed tobe worn 24 hours per day, they correct the maxillomandibular relationship inantero-posterior direction by stimulating the mandible forward into correctocclusion.