Dorfman PacificCo. Men's Big Brim Microfiber Fishing Cap

Nice light material with a large peak which gives excellent shading, the removable flap is just heavy enough to stay put in moderate wind, does the job of protecting the back of you neck from the sun. The size is adjustable and fitted my big head of 24 inches without adjusting. Don't think it's waterproof but then again it's a sun hat not a rain hat, 10/10