This is a particular indicator which was recently coded by Mladen for MT4 and looks like a great creation.

As explained by Mladen:
Theory :

There is always a need to measure if the market is "quiet" or it is volatile. One of the possible way is to use standard deviations, but the issue is simple : we do not have some levels that could help us find out if the market is in a state of lower or higher volatility. This indicator is attempting to do that :

• values above level 1 are indicating state of higher volatility
• values above level 1 are indicating state of lower volatility

Usage :

This is not a directional indicator. It should be used for volatility detection, not trend assessment - for that you have to use some other indicator and then check this one if the market volatility conditions are those that you expect