Dial centers and corners are available in a range of designs, colors, and attachment methods.
The majority of the design centers and corners are made from materials like embossed aluminum, heavy cast metal, cast poly resin, cut glass, or open-cut and etched—none of these are plastic. There are some silver and brass colored plastic corners that press into the smaller square dial face plates.
Definitions:

Here are the categories for each dial center and corner design type: