This 120 Degree Replacement Tip is recommended for general purpose engraving on uncoated metal, plastic, granite, or glass. 

The industrial diamond tips used with the engraving bits are manufactured to last a long time before they wear out. Individual results will vary based on your engraving pressure and the hardness of the material you engrave (brass and aluminum are much less abrasive than glass or granite.)

Replacement tip for the Diamond Drag Engraving Bit (#13103)