Lightweight and comfortable, breathable, thin material allows quick drying; foldable hat Free size adjustment via an adjustable strap that is integrated into the sweatband. Best suited for 55-60 cm Fastening: Drawstring Bucket Adjustable drawstrings for a secure fit: Chin strap provides good stability even on windy days Hand-wash recommended and hang to dry Suitable for everything: The casual, stylish, plain sun hat is a perfect choice for the outdoors, travel, tourism, water parks, beach, hunting, boating, hiking, gardening and other sports and outdoor activities Army Green FREE SIZE: an adjustable tape built inside the sweatband. Best fit for 55-60cm 21.65"-23.6" is it a one size hat? Yes, it has a draw cord to adjust the size. .which is great on windy days! Does this hat shade the back of your neck pretty well? Yes, the brim is wide enough to shade the back of your neck. How hot is the hat when you wear it in the sun? No --- very light-weight pretty cool and breathable. Is hat washable? Yes. It is polyester so wash in cold. Could you pack this hat flat in a suitcase or will that destroy its shape? You can definitely pack this hat flat in a suitcase when I received the hat, it came packed flat, and I believe it is meant to be a travel hat that can be folded and crumpled up, and it still retains its shape. Plus, you can bend and adjust the brimof the hat to the shape you want. What are the brim dimensions front, side and back? The brim dimensions is 9.5cm~10cm. Does it protect your neck from sun exposure? Thanks. It does a very effective job covering your face from sun exposure.