Center Height is 52 - 52.5 mm which is pre-designed and prefixed for Myford Lathe Machines. Can fit to Larger Machines by using Packing to Adjust Center Height * Bearing Base Smooth Rotation- ASSORTS 's Exclusive Feature. Can turn up-to a 42 mm diameter Metal or Wood Ball. Can be Adjusted for Various Sizes of Balls using the reference scale graduated in metric and imperial sizes.*Supplied with 2 Pcs x 3 Sided Indexable TNMG16 Tips along with a spare box of 10 pcs cutting inserts. Designed to make convex ball and cut concave curvature (* pls refer to the image in the ad) * The much demanded graduations in imperial and metric measurements are now being provided as a reference scale for turning a approx ball diameter calculations. Its is important to note that the scale provided is for a close idea of the diameter of the desired ball size. It should not be referred for an exact measurement by the users.* The insert tip should be adjusted to the given reading for achieving the desired size of the ball. Pls note the scale is a radius reading, which means that for any set parameter on this scale, you will get double of it as the ball diameter. Example- If you set the scale at a measurement of 15 mm, you will get a ball size of diameter 30 mm. The attachment has both Imperial as well as Metric graduations on either size of the attachment.