BREATHABLE&COOL: Soft mesh panels for better ventilation and keep you dry and snug.Applying Massive Durable Mesh Vent sets your head free from stuffiness. ADJUSTABLE&QUICK DRY: The adjustable strap is stretchy and has enough length. It can fit your head girth very well. You will not fill too tight or too loose. It can dry up very fast. PORTABLE & LIGHT WEIGHT: The cap crown is unstructured. so it can be folded and fit into any bag. Combined with breezy soft fabric, this cooling hat can give you a lightweight wearing. And you can take it with you to everywhere and will not occupy too much space, bring you a lot of convenience during use. SIZE GUIDANCE :(M/L)Numeric Size:7-1/4”-7-3/4” For head girth:22-7/8”-24-3/8”(58cm-62cm).Cap depth:5”(12.7cm) Bill length in the middle??3-1/8”(8cm). NOTE:*This baseball cap does not fit a samll head.* PERFECT FOR WATER SPORTS : The material will not get wet like regular cap. It will not make you feel uncomfortable if it gets wet.Ideal for runners, golfers, tennis players, and any indoor or outdoor activities. If you meet any problem before or after purchasing our products, welcome to contact us at anytime.