The Jayhawk Oval Fitting system consists of the 36 most common sizes of Jayhawk Custom Ovals, along with detailed instructions and tips for drilling oval holes. The inserts fit into the Jayhawk Measuring Ball, so you can give your customer and yourself the comfort of knowing a ball will fit perfectly before you drill it. Set includes 36 inserts - for each size there are 3 inserts: .030, .060 and .090 These inserts are machine cut for accuracy Fully adaptable to the Jayhawk Measuring Ball Set comes with an easy to use chart showing how to duplicate on your milling machine The first simple method for fitting and drilling oval holes!!