Ball head

A ball head made by Manfrotto

A ball head is a metal or plastic apparatus placed on top of a tripod that increases stability and provides faster, more accurate rotation for the photographer. They are also lighter than traditional three-way pan-tilt tripod heads. With fewer parts and a much simpler mechanism, ball heads are usually preferred by more advanced photographers. However, they are usually quite expensive due to the precision-made pieces inside and the detailed finish outside -- most professional-quality heads are more than $200 USD, although some good heads are available for less than $100.