Power Position Szela
Often, especially with beginners, I will have lifters work the clean from the power position to increase their finish of the second pull and their speed in the third pull.  However, the clean from this position can be a double-edged sword.  It is our natural inclination to want to gain some leverage over the bar by which we can apply force to the bar and create bar-speed.  However, in the Olympic lifts, leverage happens at the knee NOT at the hip.  Power happens at the hip.
If you are not careful you will find yourself working the clean from this position and creating bad habits.  Specifically, if you allow your shoulders to move in front of the bar you will create a scenario to where your hips thruster horizontally jabbing at the bar and sending the bar way out in front of you.  I created a video to talk about the point of the clean from this position and the subtle keys to doing it well.  Check it out:
The Point Of Cleans From The Hip