These ceramic safety blades retain their sharpness much longer. Because of our proprietary manufacturing and sharpening process, they also feature a finger-friendly edge. sliceĀ® donates 1% of sales to Autism research related charities. Rounded Tip. Blade Type: Utility Knife; Cutting Edge Form: Straight; Material(s): Ceramic Zirconium Oxide; Blade Length: 65 mm.