Click the image, which will take you to Massdrop.com. Then, enter PRACTICE in the search box on the Massdrop home page.
CUTAWAY MASTER COMBINATION PADLOCK - Unique Educational Aid, Awesome Novelty Gift, Unbeatable Conversation Piece!
Here's an awesome visual aid that is unmatched for teaching, in a glance, exactly how simple dial combination locks work! Made from probably the best selling padlock ever -- the series 1500 Master Combination Padlock -- this practice lock shows all. The rear plate has been completely removed and replaced with a clear acrylic back plate, so nothing inside can hide. Simply dial in the combination (provided), and as you do so watch the wheels in the "wheel pack". You'll see the magic unfold, and it suddenly becomes clear how combination locks with dials work. This same principle is used extensively in safes using dial combinations, except that they have at least one more wheel in the wheel pack to create a longer combination.
This perfectly crafted lock makes a wonderful gift, too -- a perfect conversation piece/visual aid/functioning practice lock all in one.
UPDATE - Check out the newest version of this hot selling item. We've made it modular so you can disassemble it and put it back together. No better way to learn how and why it works; and it's fun as all get out! We've sold to schools and U.S. Military, so it must be a good teaching aid, right?