Via Yanko Design
The Page Chaser is a flexible bookmark that automatically marks the page as you turn them. Ordinary bookmarks can fall out and require you to correctly mark where you left off. Why waste all that precious brain power on something so mundane? The Page Chaser catches every page as you turn. It’s an incredibly simply design that never falls out. Cheap, easy to manufacture, and handy.
Find more sketches of the bookmark here.