PETRA Sunglasses by Kirk & Kirk. Material: Acrylic, Shape: Square, Color: Earth, Sunset, Midnight, Size: 50-19-143. The PETRA sunglasses are perfect for making a stylish and confident statement under the sun. Crafted from high-quality, lightweight acrylic, these sunnies ensure both comfort and durability. The Kirk & Kirk's PETRA shades feature a bold, oversized design that exudes vintage glamour with a modern twist.