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.