Many office supply stores, such as OfficeMax and Office Depot, and online retailers, such as Amazon.com and StoresMart.com, sell clear bookmarks. Some of these are also magnifiers, serving as page-long magnifying devices. Some are not only magnifiers but also feature an adhesive like that on sticky notepads.
Office Depot and OfficeMax, which as of January 2016 were the same firm, both sell the Carson MagniMark Magnifier, a three-times-magnification bookmark that is 6 inches long and includes a ruler on one side.
Amazon.com sells a variety of clear bookmarks, both singly and in multi-packs. Some are designed to hold sheets of pictures from a standard photo booth, some have two to three-times magnification and still others have a sticky adhesive on their backs, to ensure they don't slip from where they are placed.
StoresMart.com sells clear bookmarks in quantities ranging from 10 to 1000, with pricing on a sliding scale based on the size of the order. The bookmarks are clear from the front, but shaded on the back, and come in aqua, blue, orange, salmon and yellow. They are open on one end to allow for customization, but do not fit photo booth pictures. Their outside dimensions are 2 1/2 inches by 7 1/2 inches.