An Exerpt from The First Cut Is the Most Heartrending, Jessica Lynch's SpecialOps Barber Tells All by PFC Randall Neubauer:

I see the backs of heads all day and I run clippers over every one of them. But when Jessica came in, I knew: she was different. She sat down and I looked at the back of her head and I knew: that was hair that was strong; it was resilient; it was going to go to Iraq and back and change the way we think about the Army. I used a number seven clipper.
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When Jessica came back and I saw her on the plane, I knew it was only a matter of time before The Call came. Inside of a month, they sat her down in the chair in front of me and I had out the old number seven. She asked for no gel and a light spritz of water.