Feather 71S Double Edge Razor Blades will fit in most double-edge safety razors as shown in the picture. They are sharp on both side. These razor blades are made of stainless steel and have a special coating for increased durability. Feather 71S Double Edge Razor Blades provide a very smooth shaving result, because they are very aggressive. That is why these are less suitable for men that just started out with wet-shaving and more popular under advanced wet-shavers. These blades are not suitable for men with sensitive skin. This box contains 5 razor blades. Sharpness of the razor blades 5 out 5 (aggressive) How to use the Feather 71S Double Edge Razor Blades: Place a Feather Double Edge Razor Blade in your safety razor as in the picture. Use some shaving cream or shaving soap and shave your stubble while rinsing your razor frequently. Apply an after shave lotion or balm afterwards for the best result.