Made of Plastic. It is perfect for the classroom. The two wings will hold the pages open more easily than if you just used your hand, making reading more comfortable. You can simply put the thumb thing on your thumb and pick up a book. It is great for commuters, especially if you have to read standing up. When you are finished reading, you can place the thumb thing in the top of the book as a bookmark. 3.14" L x 1.18" W x 0.79" H