Great Product!
I've been using the Credo Safety Blades for 8 years and they do a great job at removing calluses on my big toes and heels.  After scraping the areas, I use my electric buffer to make the areas really smooth.  I give this product 4 stars instead of 5 because I have nicked my toes a couple of times by scraping too close to my skin, so you still have to be cautious when using it by being aware of how close you are getting the skin.
Rating: 4 stars