The "New Approx. Cycle Cap" is a baseball cap, so you can use it with a cask or helmet. The adjuster on the back of the head allows you to fine tune the size. SHELTECH(R) material allows you to move freely even in the hot sun. Sweat absorbent and quick drying, UV protection, heat reflection, and cooling sensation. Hand washable; Material: 58% cotton, 42% nylon; Weight: Approx. 1.4 oz (40 g); Country of Origin: Japan; Product color may appear different from the actual product depending on your display settings, etc. Product specifications, logo design, etc. may be subject to change for product improvement. We also cannot answer measurements or personal fit that the manufacturer does not announce. Please be aware of