Sarah is, by a wide margin, one of the best SFM model's I've ever seen.
She has all her facial expressions points well defined.
The model never allows her eyes to move into an awkward position, and dynamically moves her eye lids based on what direction she's looking.
She has control points for her breasts, anus, and vagina.
Finally, she has also has several options for clothing, and the clothing's position including pajamas, school, and casual wear!

She was made by a modeler called Croix who just kinda vanished after making several BEAUTIFUL models for Source Film Maker. The only of his I haven't tried yet is Sunny Emmerich from Metal Gear Solid 4.

I'll find a use for her one day :)