FELLOWS 6 and 6A Series Gear Shapers, including 6A3, 61A, 612A, 615A, 645A, 61A, 62A, 64A, 624A, 62A3, 65A3, 624A3, 645A3: Detailed Operator's Instruction Manual that includes two charts for Change Gear Combinations and a formula for calculating other combinations.