The BH-55 is Really Right Stuff's largest ball head, with a probably-never-need-it 50lb (22kg) load capacity. This is a surprisingly low-profile head that's barely 10cm tall, and if you're planning to load it up with the big stuff, the lower centre of gravity will definitely help keep things steady. With 6cm Arca clamp. Like all RRS product, this is beautifully machined from high quality metal, and finished with great attention to detail. Function is excellent; there is light finish wear, mostly on the clamping portion.