The universal COKLO Clamp for the FOBA COMBITUBE is designed to form-fit around the 1" (2.5 cm) COMBITUBE sections while holding paper, reflective material, backgrounds or light gobos. The COKLO, weighing just 2.8 oz (80g), is a component of several COMBITUBE systems and is available singly and in sets of 5 and 10 units.
I use two of these to hold up a DIY window to prevent lens flare when back lighting. The window is heavy, made of 1/4 MDF wood and covered with duvetyne fabric. It weights almost two pounds. Two clamps on a vertical light stand pole hold it securely. They also work great on horizontal rods of different diameters too. With one curved side and one flat, they work great for clamping reflectors or other flat materials to curved surfaces. Swiss made - should last forever. I can't find anything else to match them. Highly recommended.