Two Sided Signal Magnet has strong magnetic attraction on both sides. One side of the magnet is red and the other side is green - This is often called GO - NO GO magnet. Two sided magnet gives you the ability of flipping the magnet over for dual purpose use.
Medium material is 0.030 inches, suitable for most uses. Thickness is about the same as a dime. This is the thickness used for magnetic car signs.
Search for "red/green" for various other sizes and shapes of red-green magnet.