Spine Full Framed Sunglasses. Inspired by the interaction between vertebrae, spine solves age old hinge limitations. Spine hinges gently flex to fit any head size, they lightly grip the face which means no more frames slipping down the face. They are durable as each part works together seamlessly, sharing each other's load. There are no screws used in the working mechanism, so nothing to loosen, and due to the dual spring and cable the temples shut automatically when removed from the face.spine lens cloths and cases available to purchase separately.available as sunglasses tints in grey, brown and green tints with uv400 protection. Click buy now and then choose your lens options.if you require lighter tints or other colours customise the frame as a prescription glasses.