Fail on history: It wasn't the Sensor in 1990 that introduced the 2 blade cartridge, it was the TRACII in 1973, followed by Atra, and then Sensor. Meanwhile, Shick had their own inventions, such as the Tracer.<p>Further, IP was such an issue that it caused King Camp Gillette to lose control of the company because his competitor held the patent to his newly invented blades. It was going to be settled by buying the competitor and giving the competitor's founder non-voting shares, but it came out in due diligence that Gillette had been over reporting profits. American Safety Razor executed a reverse takeover and kicked Gillette out... and it all began with an IP failure over blades.