The double-joint clip is the knuckle of your camera rig — it grips two ball joints at once so you can swing a light into position, tighten one lever, and shoot. The clamp locks firmly even with cold, gloved fingers and eases off just as smoothly when it is time to reframe. Salt-water-ready construction keeps it working season after season. Add one to your rig and spend the dive shooting, not adjusting.