Starrett Dial Indicators have a shockless, hardened steel gear train and are furnished with jewel bearings and lug-on-center backs. Conforms to AGD specifications. Rugged and simple unit construction with a "universally fitting" design. One gear unit assembly. Non-reflecting white eggshell finish on dial. Unbreakable crystal. Massive bridge for rigid bearing support. Hardened stainless steel bottom stems can be held in fixtures without cramping rack action. Light but sturdy, no-glare satin finish on case. Direct acting compression spring eliminates side friction. Easy readability with the best, balanced style of graduation and number combination. Balanced and tapered hands are easy to follow. Replaceable low friction jewel bearings. All gear trains are fully jeweled for sensitivity, smoothness and life. Sharp bezel serrations for positive grip. Interchangeable contact point. Positive-acting clamp locks bezel in position. .375" mounting diameter (all AGD models). Four screw holes for 90ยบ rotation of back. Special non-shock mechanism (can be furnished on most styles) is ideal for when an indicator may be subjected to repeated and excessive shocks.