First portable clocks were introduced in the early years of mechanical clock production in Europe. During 16th century engineers and manufacturers finally gained the ability to created devices on such small scale that people could carry it with them, but those initial models were way to big and heavy for pocket and wrist. Instead, first portable watches were worn on a neck pendant. Other disadvantages were very bad accuracy (even though they had only hour hand, they could lose several hours during one day), noise, durability and bad protection from outside influences (hour hand was not protected by glass, but only with hinged brass cover).