●2 Arm Dimensions: 4" upper arm, 4.5" lower arm, 14.1" overall length ●With fine-tuning: with fine-tuning switch, suitable for high-precision adjustment. ●With two control switches: Provides 176 lbs of maximum pull force (requires use on metal/steel with a thickness of 1.2"/3cm), flexible, strong, precise rotary joint, adjustable in any direction and position, with high stability. ●Clamping Diameter: 3/8" (9.55mm) for regular inch dial indicators; comes with brass ring, 5/16" (8mm) clamping diameter when installed, for digital dial indicators and metric Dial indicator.