Bucket hat is popular in recent years. A bucket hat can match many clothing style. In the past, bucket hat is popular with fisher man. So it is also named fisherman hat. The traditional bucket hat has drooping brim. It is good at blocking the sun.
（picture from gladstoneobserver）
Now many fashion girls and boys prefer bucket hat for blocking the sun or fashion style. For daily suit, blocking the sun may not the most important function. To be fashion can be more important. The traditional drooping brim usually block the line of sight, which makes users uncomfortable. Then some manufacturers add a piece of TPU coated aluminum wire at the edge of brim. Within the soft TPU coated wire, the brim of hat can be shaped into any style you like.
Some may say that iron wire can also has good effect on shaping. But iron wire is easy to get rusty, then destroy the hat. On contrast, TPU coated wire will not only get rusty but also stink-proof. TPU is a kind of eco-friendly plastic, which has no harm to health. So even has higher price, TPU coated wire is a better choice than iron wire and PVC coated wire.