Ever Ready Corn & Callous Knife Replacement Blades 4s Easy to insert Surgically sharp carbon steel blade Contains 4 blades For use with the Ever Ready Corn & Callous Knife. Instructions for fitting a new blade: Hold the Corn & callous Knife with the blade holder curving away from you as illustrated. Keeping thumb & fingers away from the blade's edge facing right, carefully insert the point of the blade into the tip of the knife. Then flex the blade & push the lower end to the left of the retaining hook. Only use in the Ever Ready Corn & Callous Knife. Caution: Diabetics & people with poor circulation should consult their Doctor or Chiropodist before using this product.