This Penc Cup Tray is compatible with our Rolling Whiteboards and Glassboards by Merge Works. It easily fits several markers, pens, or pencils to keep your accessories organized and out of the way. The opening in the cup measures 4" wide by 4" high (2" x 3.24" opening and 4" deep.) The acrylic finish gives it a clean and elegant look. Don't order a whiteboard without one of these... Order now!