The Starrett 25 Series Dial Indicator has a shockless, hardened steel gear train and jewel bearings, except where noted. It is furnished with a lug-on-center back. Anti_magnetic mechanism is optional for all models. Special non-shock mechanism is available for all models except 25-109, 25-209 and 25-116. 25-261J with 8mm Stem, 0.002mm Grad.