Main Features: Transparent lock case lets you see clearly all parts inside! When lock and unlock, you can watch clearly every part how to work. When the key inserts into or out of the plug, you can see the pins moving down and up. Let you know how the shear line come out. It is the right practice lock for beginner to study how to open a lock, and know about the structure of a padlock. It is also regarded as a funny and fantastic gift or toy.