Ultimate Edge Sharpening Kit. Contains: Gleason Guide, PingRing (sharpness tester) & Diamond Head Ceramic Stone (maintain edge). To use, just hold the PDT-Gleason Guide on top of a sharpening stone with one hand and sharpen with the other. The built-in stop and angle rest help keep the instrument perfectly angled as you glide the instrument along the guide. Stainless steel construction is fully sterilizable. The stone needs no water or oil and is guaranteed not to pit or groove.