1. [Moisture Wicking & Quick Dry] The moisture wicking material and mesh design can easily absorb sweat and dry quickly in hot summer. Our skull caps are made of skin-friendly fabrics which will give you a baby-soft touch when wearing them. 2. [UV Protection/UPF50+] Our cycling cap can protect against sun and UV rays in hot summer days and protect your skin from sunburn when you are outdoors. The cycling cap is made of polyester, 1spandex. The skin-friendly icy material provides a cool feeling and is so light that you will hardly notice this hat. 3. [Lightweight & Durable] The helmet liner cap is soft and lightweight, easy to put in your pocket after use. High-quality sewing makes the durable and elastic fabric of our skull cap resist wind, dust and dry quickly. Repeatable hand or machine wash without shrinking or deforming. 4. [Universal Size] Our helmet liner cap has high elasticity. It does not put pressure on your head, easy to wear and adjust. One size fits most adults and children, fits snugly on the head and is comfortable to wear with a helmet, hat, or alone.