US crochet terms are used.

For the cozy itself, a small amount of gray is used. Leftovers from another project would work well, and anything in the gray/beige/brown family should work.

The sample used nearly a full 3-oz skein of white yarn, to cover a relatively small roll of toilet paper. If you are making a cover for a larger roll, you may need to buy a second skein or a larger skein.