The open clamp is used to attach tubes having different thickness (diameter 15-34mm, including hexagonal tubes) to the hexagonal tube. Although fine angle adjustment is possible with the gear joint, more stable setting can be achieved by limiting the movement only to the vertical direction.
HEXRACKII clamps get a rock solid grip on the rails with a synthetic sleeve that fits between the clamp and the rail. As the clamp tightens, it compresses the sleeve to establish a solid grip. This gives the clamp a secure, slip-free hold on the rail when tightened, and allows easy adjustment when loosened, making the whole setup process quick, easy, flexible, and solid.