Does the curve side of collar go under the chin or across the lower back area

The curve side goes under the chin.

My wife's neck is 18" around and quite short, about 2" high. Will this fit.

The neck brace will work on those with a neck circumference of 22" to 25". The collar is 3.5" on the side, 3" in the front, and 2.5" in the back.

How should the collar be cleaned?

We recommend a cold wash on a gentle cycle in a washing machine, line dry only, and do not iron it.

What is the strap that secures to close made of? Is it a slick finish?

The strap is made of cotton and uses velcro to keep the cervical collar tight and secure. Thanks for asking!

Do you have color choices (black or gray)?

Unfortunately we only have one color.