This lobe indicator tool measures lobe lift and base circle runout by sliding down into the lifter bore, being firmly held in place with heavy-duty O-rings on both ends, and sits atop the camshaft for measurement via dial indicator. 0-1.000" included dial indicator (sold separately as p/n 66962), reads in 0.001" increments. Includes two followers: one for flat tappet and one for roller cams.