This mesh helmet is a must for any beekeepers that works their hives when it is hot outside. This is a one size fits all helmet. The interior headband has a terri cloth headband that is on the forehead part of the helmet. The headband can expand or contract to you head size. The mesh helmet allows the heat from the beekeepers head to evaporate out of the helmet for maximum cooling. The helmet also comes with a chin strap to keep your helmet on during windy days. Helmet is built to last many years of beekeeping. Excellent helmet!