Diamond coated round section steel hones (fit your own handle) for sharpening blades such as ring tools and hook tools. Also performs well instead of a slipstone to take the burr off the inside of gouges. Tapering from 4mm to 10mm, the coated portion of the blade is 150mm long. Fine grit, British made, stainless steel, excellent quality
Works on tungsten carbide as well. Can be used wet or dry. Very useful in the kitchen as a knife sharpening steel but keep that a secret!