Gann Wheel Square of Nine Gann Wheel price and time hand calculator for forecasting stocks and commodities price movements. — Based on the Square of nine square root chart made popular by W.D. Gann. — Calculator measures 16"x16" white plastic base with a 12.5" clear plastic moveable wheel — Comes with user manual and can be used with any book about W.D. Gann (such as Patric... more »k Mikula's books) including Gann's own works.« less