The second hole at the edge is useful when uprights are placed next to a wall.
Extruded holes guide the upright into the base easily, without cross-threading.
In Nipples are attached to the upright with four steel rivets and are designed to be replaced using simple hand tools. Click here for larger view. The main advantage of the Screw-In System is the ability to stack the bases, which requires much less space. The bases are easily transported using Georgia Expo Storage Carts.