The buildup of hard skin (corns and calluses) is your body’s natural protection against pressure and friction. You do not want to remove too much skin during one use. Thin shaving from gently-applied pressure is recommended, which is why PediFix’s Safety Trimmer is flexible, not rigid. Soak area to be treated in warm water. Dry thoroughly. Hold Trimmer against skin and gently apply light pressure while drawing Trimmer toward you – always in the direction of the handle. Changing Blade: Please be careful; blade is very sharp! As shown, hold Trimmer handle with one hand and place the head of the Trimmer on a hard surface with the black blade-holder side down. With your other hand, firmly grasp the outer edges of the black blade-holder. Keeping the black blade-holder stationary, push the Trimmer handle down slightly and slide it forward to detach the blade-holder. You can now either reverse the blade or replace it. To re-attach blade-holder, reverse directions above and remember to keep the black blade-holder stationary and on a hard surface.