M3 stylus with 0.3 mm diameter ruby ball, tapered carbide stem, and 4.0 mm diameter x 17.0 mm long stainless steel base. Minor stem diameter is 0.2 mm; major diameter is 1.0 mm. Overall stylus length is 21.0 mm. Stylus weight is 0.85 gram. Compare to Carbide Probes 261-.3R.