I bought this turntable for a 4" turntable to get more out of the table but am very disappointed with the poor quality and the design of this spacer plate set. First, there are no instructions on how to assemble or how to use it. They included a half-sheet table of turns/hole counts for the various pitches of the circle, but that only gives the bare minimum of information. After figuring out how to assemble it (using instructions from an external website), the round spring component fits so tightly that it's difficult to rotate the sector arms, and I risked deforming and damaging the spring when i tried to install them properly. Overall the fit and finish is as poor as it gets and with the spring being so firm it will be very difficult to set it up for use without damaging the Sector's plastic arms.