My current animal hood is worn out, so I bought this intending to use it for diving this year, but it was too small and I couldn't wear it (T^T) Animal hoods are highly regarded for being noticeable in the ocean, making it easy to spot others in your group, which is reassuring! (≧∇≦)b I always wear a cap because body heat escapes from the head. For children or those with smaller faces. This hole (photo 3) is for releasing air. Fleece lining Head circumference: 52cm Neck circumference: 32-38cm (Velcro) It has some stretch, so it can accommodate up to 2cm larger. Please be aware of fold wrinkles. They will disappear with use.