One key to a high quality blade is its ability to stay sharp for a long time. Ceramic blades stay sharp longer than traditional metal blades so you get more use. These blades are easy to use due to the size and shape. They are usable with any tool requiring a #9 razor blade. Metal marks on stone and tile surfaces require additional clean up their use. Ceramic blades are non-metal and do not leave marks on the stone or tile. Furthermore, metal blades left on a surface in a damp or wet environment can rust and create a stain that must be removed with rust remover. Yet, ceramic blades do not rust so they won't leave rust stains on surfaces if left for a period of time. Finally, to prevent rusting, metal blades are oiled. This is great to keep the blades free of rust, but the oil can be transferred while cleaning seams. As a result, the oil can bleed into the glue and diminish the quality of the project. Additional Details ------------------------------ Product description: One key to a high quality blade is its ability to stay sharp for a long time. Ceramic blades stay sharp longer than traditional metal blades so you get more use. These blades are easy to use due to the size and shape. They are usable with any tool requiring a #9 razor blade. Metal marks on stone and tile surfaces require additional clean up their use. Ceramic blades are non-metal and do not leave marks on the stone or tile. Furthermore, metal blades left on a surface in a damp or wet environment can rust and create a stain that must be removed with rust remover. Yet, ceramic blades do not rust so they won't leave rust stains on surfaces if left for a period of time. Finally, to prevent rusting, metal blades are oiled. This is great to keep the blades free of rust, but the oil can be transferred while cleaning seams. As a result, the oil can bleed into the glue and diminish the quality of the project.