Cisco - Swivel Base - The swivel base is composed from a solid aluminum and stainless steel construction.  The inner workings of this unit are operated by thrust bearings and ball bearings for a consistent and smooth rotation.  The base indexes every 22.5 degrees for 16 different positions available for use.  To ensure years of dependable use the unit is secured in position by a stainless steel pin by mating with tapered holes in the hard anodized indexing wheel.  Unlike other swivel bases, this unit is designed so that the more the unit is used the better it locates as it wears into the tapered holes to ensure that no "slop" ever occurs.