AccusizeTools - MAGNETIC BACK WITH 0-1" X 0.001" DIAL INDICATORS, EG08-1600 Measuring Range: 0-1&#034;, Accuracy: 0.001&#034; AGD 2 Style, lug back with 1/4 hole Satin chrome finish Rotational bezel with clamp for easy zero set Interchangeable hardened contact point Sizes 2-1/4&#034;diameter x 9/16&#034;. Permanent powerful magnet. Attaches to the back of 2&#034; diameter dial indications.