Most of the ones I've seen can go full cold to full hot, or at least very close. Most also have an adjustable stop screw to limit how far they can go toward "hot", as a safety measure.
Models are available with and without volume control.
To see some examples, Symmons' website is pretty good. Go to
Eric Law
a somple answer from someone who has one.
range of temp, you can't get full hot or full
you can at least get cold and hot)