I purchase a cheaper 6 inch lazy Susan bearing to act as a fulcrum point on my garden railways turntable. The bearing was correct to what it stated on the package but when used as this purpose was not suitable because there is a drop of some 6mm each time the turntable moved 180 degrees. I therefore started again by using a larger diameter bearing which uses the fulcrum point at the end of the bearing rather than in the middle, consequently there is no drop as the turntable is supported by the entire length of the bearing rather that in the middle. I might add there is some resistance in the movement which is more suitable in what is required.