The Fowler 52-730-005-0 Metal Etching Pen is ideal for any tool room and machine shop for general marking purposes. This metal etching pen is used on copper, copper alloy, stainless steel, hardened steel tools, castings, etc. Use it to initial personal tools or to restore graduations on rules, height gages, calipers, micrometers, etc. With its low-cost and disposable design, you can carry out limitless applications of your choosing. This product has a 1-year warranty offered by Fowler High Precision. Fowler, an American company, manufactures inspection and measurement instruments such as electronic indicators, calipers, bore gages and micrometers. The company founded in 1946, is headquartered in Canton, MA.