What material is primarily used for frame fronts, known for being sturdy, slim, and lightweight?

The material primarily used for frame fronts that is known for being sturdy, slim, and lightweight is polyamide. Polyamide is a type of nylon that is often utilized in eyewear due to its excellent durability and flexibility. It can be manufactured in thin sections while maintaining strength, which helps to create a sleek and stylish design in eyeglasses.

The properties of polyamide also allow for a variety of colors and finishes, which can add aesthetic value to eyewear. This material's lightweight nature enhances comfort for the wearer, making it a popular choice in the optical industry.

In contrast, options like carbon filter and wireframe do not accurately describe a material suitable for frame fronts. Wireframes, while lightweight, typically do not offer the same level of sturdiness or versatility in design as polyamide.