These Gillette Mach3 razor blades were manufactured using proprietary three-blade technology. They fit right into your existing Gillette razor. The blades are equipped with microfins that allow the blades to get very close to your skin so that you'll enjoy as smooth a shave as possible. The blades come with indicator strips that fade to white when contact with your skin isn't close enough to provide a good shave. The indicator strips also contain lubrication that helps protect your skin.