The Percentage Price Oscillator (PPO) is a popular and useful free Forex indicator that is available on MT4. It is a momentum oscillator that measures the difference between two moving averages as a percentage of the larger moving average. It is used to identify momentum shifts in the market, and can be used to identify trend reversals. The PPO is a versatile indicator that can be used in a variety of ways to help traders identify market trends and make better trading decisions.