The inverted pyramid is a powerful metaphor for the support Six Sigma requires to succeed. At the bottom of the pyramid, supporting and balancing the structure, is the executive leadership, whose vision and values form the foundation, and without whose commitment the entire enterprise would crumble. At the top of the pyramid is the customer, around whose expectations Six Sigma quality is built. Between the executives and customers are the four types of players in Six Sigma: champions, master black belts, black belts and green belts.