We have 4 or/more of these Great Smooth working Mitutoyo Model 2923S-10 Dial Indicators with +/- 0.0001" Accuracy for sale. They work great for a Sunnen AG300 Pin and Connection Rod Gauge. Top Quality Brand with smooth accuracy of 0.0001" inch with the zero having the + plus and - Minus sides. Its face is 2" Diameter, and has a 0.055" travel.. The thread in end should be correct to fit your Sunnen AG300 or AG400 Gauge properly. If you want this Dial Indicator for other uses, you can thread in any length adapter you want. This will be packaged properly for safe shipping to you if you need that. Or Call (952)854-5 seven eight six