This dial is equipped with a single spline 5 ⁄16” - 40 spindles. A spindle is pressed into a dial with its spline keyway aligned to either 41 or 50 on the dial. The #41 splining location is required to ensure full lock bolt extension when key locking dials are locked down with zero under the opening index. Dial spindles will accommodate a maximum door thickness of 3.4 inches (86.5 mm).