Double fine adjustment. Bottom: unique single direction Top: universal swivel clamp Holds 6mm, 8mm, 3/8" and dovetail and back lug. Unique central locking mechanism with Noga designed spring loaded bearing. Instantly fastens in any position. Fast and easy to set up gauges into required position. Aluminum material with black finished arms. 5 axis holder. Base Type: Standard Magnetic Pull (LBS): 176 Base Material: Steel Arm Style: Articulated Arm Fixed Arm Length (Inch): 4.3 Branch Arm Length (Inch): 3.98 Clamping Diameter: 3/8, 6mm, 8mm