Safety razor become locked into buying their proprietary cartridges, for as long as the manufacturer continues to make them. Subsequent to introducing the higher-priced Mach3 in 1998, Gillette's blade sales realized a 50% increase, and profits increased in an otherwise mature market. The marketing of increasing numbers of blades in a cartridge has been parodied since the 1970s. The debut episode of "Saturday Night Live" in 1975 included a parody advertisement for the Triple Trac Razor, shortly after the first two-blade cartridge for men's razors was advertised. "Mad" magazine announced the "Trac 76", arranged as a chain of cartridges with a handle
Safety razor with its "Gem" models. Although these brands of single-edge razors are no longer in production, they are readily available in antique trade, and compatible modern designs are being made. Blades for them are still being manufactured both for shaving and technical purposes. A second popular single-edge design is the "Injector" razor developed and placed on the market by Schick Razors in the 1920s. This uses narrow blades stored in an injector device with which they are inserted directly into the razor, so that the user never needs to handle the blade. The injector blade was the first to depart from