Take your time choosing a composition - frame your perspective with the ViewCatcher. Useful for framing and composition for fine art, crafts and photography, the device slides open to provide a viewing window that features indicators for standard proportions used for framing purposes, such as 8" x 10", 12" x 14", etc. , it has a convenient thumb grip for opening the viewing window. A small round opening in the center of the sliding window allows you to determine the value of the colors your are viewing. Durable, mid-gray, ABS plastic construction Opening is 1-15/16" at its largest point Comes with an 8-page instruction booklet