This boom attaches to the shaft of most light stands and gives more lighting possibilities. Great for product photography or holding a hair light. Designed for stands with diameters of 19, 20, 25, 28mm. Ø: 25mm. This arm complete with Pivoting Clamp 124, Counter Weight 023, cable clips and locking key. Arm tube diameters: 25mm.; attachment: type25 + spigot art. 013; color: black; counterweight: 9.48 lbs.; load capacity at maximum extension: 6.61 lbs.; material: aluminum; maximum extension: 78.74 in.; minimum extension: 27.95 in.; 3 sections; weight: 12.57 lbs.