This bundle includes the Rule of Thirds + Fibonacci (aka Golden Ratio) + Golden Triangle Viewers. Both are great tools to help any artist compose your image. Whether you're a photographer, urban artist, or plein air painter, use these viewfinders while composing your photographs or paintings. The Rule of Thirds Viewer has a dot in the center to help you line up your composition more easily and is the exact proportion of 35mm full frame DSLR/Mirrorless cameras (3:2), so you'll get your composition just right. Use these viewfinders before you press the button or commit paint to canvas. Use all three viewfinders as a non tech tool to help your kids interact with the environment; looking for these patterns in the environment is fun and challenging. Both patterns are etched into crystal clear, 2mm, acrylic making them completely waterproof and nearly unbreakable. The size of a credit card (85.6 mm X 53.98 mm x 2mm) they can be kept in any wallet, camera bag or plein air painting kit.