What material are they made out of? They are made from polyurethane resin hand cast into molds. How do I attach them? This is depending on the material you want to attach them to. We suggest a either a medium to thick super-glue or epoxy glue. What types of Bezels are available? There are 2 basic shapes, round and square in different sizes. Plus there is a special bezel for the HSI and a 3-part engine gauge bezel.