Magnetic-Base Indicator Holder Arm Type Rigid Base Height 2 3/8 in Base Length 3 in Base Size 3 in L x 2.375 in W x 2.375 in H Base Type Magnetic Base Width 2 3/8 in Compatible Indicator Mounts Lug-on-Back Fine Adjustment Position Fine Adjust Top (FAT) Holding Power 150 lbf Maximum Reach 15 in Step Type V Step Working Length of Post/Lower Arm 9.375 in Working Length of Snug/Third Arm 1 in Working Length of Upper Arm 9.375 in Base Thread Size 1/4 in-20 Construction Cast Iron