Blackboard Coasters - These unique coasters are made with a special UV coated vinyl that you can draw on with regular chalk and then wipe off with a damp cloth for their next use. The cool thing is the cork backs have a small, strong magnet embedded in them so you can store them on the fridge when you're not using them. Each magnet is counter sunk so the back surface of the coaster remains flat. They can become mini blackboards for your lists OR they can be used as regular coasters OR they can be used like name cards for a dinner party Each coaster measures 3 1/2 inches ( 9cm.) in diameter. They come in a set of four with a 4-pack of chalk. Makes a unique housewarming gift or fun gift for the college student!