Brown & Sharpe TESA 01866010 Stainless Steel Contact Point with Ruby Ball Tip, 0.6754" Length, M1.6 Thread, 0.031" Stem Dia. TESA contact point for use with Brown & Sharpe Interapid series dial test indicators Ruby (synthetic sapphire) ball tip for light weight, wear resistance, stability with changes in temperature, suitable for delicate and silicon carbide surfaces, and non-magnetic and non-conductive properties for use in Electrical Discharge Machining (EDM) processes M1.6 thread