Holt Allen's Ball Bearing Mini Swivel Base was developed with the demands of the high-performance 49er Class in mind. The 49'er's ballet artist/helmsperson requires minimal play in the jammer's bearing system, maximum cam performance, and super smooth swivel base rotation at difficult or extreme angles. This is especially true during exciting mark roundings. We've left it up to you to select your lucky block that will react instantaneously and telepathically so your boat will always remain upright. This Mini High-Angle Wire Frame Swivel Base can be used on smaller high performance boats too.