How long a razor blade refill lasts is dependent on many variables such as beard toughness and thickness, beard preparation, shaving habits, and skin sensitivity. The Gillette Fusion5 ProGlide Power's reformulated Indicator Lubricating Strip (vs. Fusion5) will provide you with a visual cue—it fades to white—when optimal shave conditions have been reduced. When this happens, you might want to consider changing your razor blades to get an optimal shave.