The pack is based on a study the artist did in honor of the late, great David Bowie. Avila made a PDF explaining each muscle of the face and neck for anyone who wants to use as a reference or study.
The best thing is that the pack also features the Zbrush File for you to study the full 3D model.
It is an awesome chance to study all the aspects of facial anatomy in detail and start creating your own sculpts.
Do you know some other great reference packs or books to study anatomy? Please share them in the comments.