Choosing Yarn for a Project

Hi I’m planning on knitting this hat, here’s the pattern:
I wanted to make this hat but I had a specific yarn in mind to use, here’s the yarn I want to use:
It says the yarn should be knit with needles size US 5-9. How come this yarn says you can use a variety of needle sizes? I’m just wondering because there’s a big difference between a size 5 and a size 9. In what case would you use what size needle? I’m just trying to understand since the hat pattern says to use size US 7 needles. Would this yarn work for the hat? Thanks!

Ooh, that angora yarn is yummy. Angora is very fluffy and can be knit over a range of needles. Indeed many yarns can depending on how closed or open you would like the knit fabric to be. Angora especially will fill in when knit on the larger needles.
The best needles to use are the ones that give you the gauge that you need using your particular knitting tension. Knit up a small swatch to see what the knit fabric is like as well as to determine needle size. (This isn’t so straightforward with angora since it’s difficult to rip out the swatch in case you need the yarn but may be worth a try.)
You may lose a bit of the definition of the stranded work on the hat but the angora will be gorgeous.

Okay thank you so much!