Padlocks are a portable lock that may secure valuables that cannot be traditionally locked. A padlock consists of the actual padlock body, and the shackle. The shackle is usually a U shaped loop of metal and is locked onto the body of the padlock, in some cases a hasp is used to lock a building. The shackle is the most vulnerable part of the padlock. Many different types of padlocks are available from brass padlocks, to weather resistant padlocks. Some padlocks use their own special hasp to lock, and do not even have a shackle, these are called shackless padlocks.