This 10-inch portable fan from O2Cool operates on two speeds and has a convenient, built-in handle. This easy-to-carry fan takes six D cell batteries but can run using an AC adapter. On a full battery charge, this petite yet powerful fan can last up to 40 hours. This O2Cool fan model is perfect for outdoor events as well as hot indoor environments. The unit weighs about 2 pounds, making it great for on the go use.