The Skeletal Mesh used to estimate the skinning deformations during compression. To add an asset, use (+) Add and then select an asset from the drop-down menu. This property is meant to ensure optimal visual fidelity is retained during compression. If you can provide The ACL codec with a Skeletal Mesh reference, the codec will not have to approximate the visual mesh, improving the results of compression. However, with higher fidelity meshes, the memory footprint tends to increase slightly.