This is a crocheted beret hat. The circumference is approx. 30.79 inches and can be adjusted easily which is explained in further detail in the pdf pattern.
This pattern does not include the type of yarn because this was a very old project, materials have been lost or completely used. Howver, at the time of my earlier crocheting, I have been known to use mostly redheart yarn from JoAnn Fabrics. This is most likely red heart brand.