Really Right Stuff's biggest ball head, the BH-55 is beautifully made and finished from high-quality steel and aluminum, with a load capacity of 22kg. This BH-55 is in good cosmetic condition, with a few surface scuffs and wear from use. Ball lock is almost criminally effective, plate clamping is secure. A fantastic large ball head suitable for nearly anything you might be able to throw at it. Base fitting is a standard 3/8" thread; base diameter is approximately 72mm. Plate is not included, but this is compatible with most any Arca-style plate or bracket.