Features: 1. Sweat absorption and quick drying: Sweat-wicking material and mesh design can easily dissipate sweat and dry quickly in hot summer. Our skull caps are made of very skin-friendly fabric that feels like a baby skin when wearing. 2. Fits comfortably under your helmets designed for bicycle helmets this lightweight and thin summer hat can be worn comfortably under a helmets and protects against sweat 3. Lightweight and durable: The helmets cap is soft and lightweight you can simply put it in your bag after use. High-quality sewing craft makes our skull cap stretchy protects against wind dust and can dry quickly. Repeatable washing by hand or machine does not shrink or deform. 4. No overheating designed for use in hot summer as protection against sunburn on the head the thin mesh material of this cap is highly breathable and prevents heat build-up 5. Wide application: ideal for many outdoor sports occasions. You can wear this skull cap as a helmets lining for bicycles motorcycles baseball or alone when running jogging hiking fitness etc. Keep your head breathable and dry at all times. and the simple style makes you look stylish and cool. Notice: 1.Actual color may be slightly different from the image due to different monitor and light effect 2.Please allow 1-3cm deviation due to manual measurement Description: Suitable for head circumference: 52-60cm Size: 25.5x16.5cm includes: 1x Lightweight Bicycle Underhelmet Hat "