Keys
A key is a common unlocking tool in people's life. The materials used for making the key are mainly copper, zinc, aluminum, iron and other metals. The key was invented later than the lock, which appeared in ancient Egypt 4,000 years ago. There are many types of keys, including ordinary keys, smart keys, remote keys, electronic keys and so on. Keys are people's daily necessities, and as time goes on, the daily necessities of the past have evolved into collectibles. The keys are mainly...