Razor be used on both sides, with two open edges. The blade on the double-edged safety razor is slightly curved to allow for a smoother and cleaner shave. In 1901, the American inventor King Camp Gillette, with the assistance of William Nickerson, patented a new variation of safety razor with disposable blades. Gillette realized that a profit could be made by selling an inexpensive razor with disposable blades. This has been called the razor and blades business model, and has become a very common practice for a wide variety of products. Many other brands of safety razors have come and gone.
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