The best way to understand it is to build it yourself! Our Secure Pro DIY Padlock Assembly Kit allows you to understand the use of each part of a padlock, from the tiniest pin to the shackle and springs. If you want to see all the movement of the pins and springs, a clear acrylic shell is the only way. The polished molded shell features the pins and springs designed specifically for this practice lock. Once the padlock is built with the included parts, use the included key extractor tool and tension wrench tool to practice picking it. Suitable for 12 years and up, this kit makes a unique gift idea and is a really cool way to teach kids how locks work.