From Manufacturer
The Acratech Ultimate Ballhead is the result of innovative efficient design, created for combining low mass with incredible stopping power. Available with or without an installed Arca-type quick release clamp, it is an ideal head for those that do not require the progressive tension control of the heavier (and more expensive) Arca-Swiss B1.
The innovative design of the Acratech gives the photographer full access to 25% of a sphere at any time, and it is entirely capable of providing support in any direction so long as the tripod legs are not overwhelmed.
Model #1116 features rubber knobs on the left side of the head, which are more comfortable to operate in cold temperatures. It does not feature a camera platform, only a 3/8" screw. This would be ideal for users that already own their own quick release system, and do not want to switch to the Arca type system.