This knife is a practicable sheath knife. The shape of our blade is a double-sided mirror-finished convex surface. This is a technology that doesn't permit other follows, and we have confidence in this surface. When you strongly press this knife against the telephone book, it will cut like cutting butter. Please confirm our HONZUKURI blades that evolved. ZDP189 is a powder stainless steel material developed for cutlery. It is a product of the nano tech. Sharpness did not decrease so much to the blade of ZDP189 after having cut hard Manila rope 780 times. However, it is an unsuitable knife to the beating cut. This knife is full tang.