Shape Keys Extra provides a suite of tools for managing and manipulating shape keys in Blender. Users can mirror shape keys across a model for perfect symmetry or blend multiple keys together to generate new custom shapes and expressions. The toolset allows you to apply modifiers, such as subdivision or armature, without destroying existing shape key data. Additionally, it includes a transfer feature to copy shape keys between different objects, and a bind cloth tool specifically designed to attach garments modeled in alternate poses, such as mapping an A-pose shirt onto a T-pose character.