... whetting speed and quality greatly, small and flexible design, Knife Sharpener adopts two pieces whetting design,which increases the whetting ... shapener,hold the rhombus protuberant part by hand, put sharpener vertical to the table top,that nonskid soft rubber ... perpendicularly;make an effort slightly to pull hereafter the knife,repeat several times, till the blade sharper. Diamond Knife Sharpener