Over time, the blades of the Philips OneBlade need to be replaced. If they're used a lot, it's best to replace the Philips OneBlade blades after 4 months. If you don't use them as often, the blades will last much longer. The useful wear indicator indicates when it's time to replace the One Blade razor blades. If the wear indicator is green, then it is time for new razors.
