From the product page (typical FullFace pack):
used by character artists to create hyper-realistic skin details TexturingXYZ- Female 20s FullFace 24
: These packs often include utility maps containing hemoglobin and melanin estimations, which are vital for achieving realistic Subsurface Scattering (SSS) and skin tone variations. Workflow Integration From the product page (typical FullFace pack): used