Articulated arms are a great accessory for any studio application.. Features as 143N, but a large locking knob takes the place of the cam-lever. Variable friction and locking of arm obtained by adjusting knob. Arm tube diameters: 20mm.; attachment: type 17; attachment 2: type 17; black color; load capacity: 6.61 lbs. material: aluminum; weight: 2.40 lbs.