You know how Martingale works - you buy 1 and you lose, then you buy 2. So every time you lose, the size is multiplied by 2. After profit, you don't need to multiply, so the value is 1. You can change the values if you want to change it. For example, the Anti-Martingale strategy is the opposite - you multiply on profit and reset on loss. With the default values you have the original Martingale.
