The MICRO series comes in two different sizes. Part number MICRO-1 uses standard type SF or SR drill bushings with a 1/2" O.D. X 1/2" long. Part number MICRO-2 uses 3/4" O.D. X 3/4" long bushings. They don't pivot but are so small 'they go where no other bar has gone before'. They both have three slots to increase clamping positioning, may also be clamped down with c-clamps.