This is Dave Powell’s latest Spirit Slates which is essentially a larger and better quality version of the old CW effect the Slates of Solomon which in turn were basically the same as Milson’s (yes before Milson-Worth) Satyr’s Slate c. 1971. This set of spirit slates works without any flap or outside gimmick. It is ingeniously designed with the mechanism actually inside the slate.
Effect: The performer displays two old-fashioned chalkboard slates that are truly blank on both sides. The performer rubber-bands the two slates together and places a small piece of chalk in between them. Two spectators each choose a card and, when the slates are opened, the name of one of their cards appears written on one of the slates as if the spirits had written it! The writing on the slate is erased and the rubber bands are again put on the slates. This time the second card appears written on the slate. You can just have one card predicted or you can have one card predicted on one side of the slate and another on the other side. Instantly Repeatable! No Set Up, Always Ready! Each Slate measures 4.5 x 5.5 inches.
(Notice: Includes: Printed Instructions.)( Post Source: martinsmagic.com - click for details )