COOL FEEL & UV PROTECTION: Thanks to high-quality, breathable fabrics and the extended bicep design, these arm warmers block more than 98% of harmful UVA and UVB rays under the arm. Newbyinn's arm warmers offer more UV protection than other products. CHOOSE THE RIGHT SIZE: M is for biceps of 9-13.5 inches and L is for biceps of 11-15.5 inches. If you have large arms, you don't have to worry about them restricting your biceps or being so long that you wonder if they're for kids. Unlike professional compression sleeves, these cooling arm sleeves provide enough compression to keep them in place. They're so comfortable that you'll forget you're putting them on. Compression. Coverage. Protection. Sun protection SUITABLE FOR ALL SPORTS & OUTDOOR ACTIVITIES: No matter the season, our lightweight arm sleeves protect your sensitive arms when exposed to the sun for extended periods. In addition to excellent breathability and sweat wicking, they also serve as protection against scratches during various ball games or while climbing. They can be used for football, golf, basketball, fishing, cycling, hiking, driving, etc., making them even more fun for users. EXCELLENT TATTOO COVERAGE: We respect personalized tattoos and various professions. But covering tattoos with long-sleeved cotton shirts is a thing of the past. Use these arm sleeves for protection. The blend of nylon and spandex gives you a professional look without breaking a sweat. Black, dark gray, navy blue, and other colors are available. (WHITE may be slightly see-through) WASHABLE & STRETCHY: Our arm sleeves are extremely durable and stretchy. Easy to machine wash and hang to dry. The 90% nylon and 10% spandex blend is suitable for men and women. You can always find a way to cover your arms with these arm sleeves. Leave one pair in the car and another in your pocket. Swap them out at work or share them with your team. Sold as 2 pairs or 4 pairs. 4 pairs is the more economical option.