These Silver bars and rounds from APMEX feature innovative design elements making them easy to stack and securely store. They are a great way to purchase more .999 fine Silver with fewer physical pieces. The Silver rounds feature a raised, textured rim to allow for easy stacking and storing. The APMEXclusive® interlocking ridges were specifically designed to allow you to create a stack of as many 1 oz Silver rounds as you like. You can indeed see, feel and appreciate the innovative production and stacking design.