Razor razors were the most common form of shaving before the 20th century and remained common in many countries until the 1950s. Barbers were specially trained to give customers a thorough and quick shave, and a collection of straight razors ready for use was a common sight in most barbershops. Barbers still have them, but they use them less often. Straight razors eventually fell out of fashion. Their first challenger was manufactured by King C. Gillette: a double-edged safety razor with replaceable blades. Gillette's idea was the use of the "loss leader" concept, in which the razors were sold at a
Safety razor the second blade cuts it further. The extent to which this is of practical consequence has, however, been questioned. Gillette introduced the first triple-blade cartridge razor, the Mach3, in 1998, and later upgraded the Sensor cartridge to the Sensor3 by adding a third blade. Schick/Wilkinson responded to the Mach3 with the Quattro, the first four-blade cartridge razor. These innovations are marketed with the message that they help consumers achieve the best shave as easily as possible. Another impetus for the sale of multiple-blade cartridges is that they have high profit margins. With manufacturers frequently updating their shaving systems, consumers can