CNC turned in Black Walnut and hand finished. They are roughly the size of a cue ball and fit perfectly into the human palm. We use regionally harvested American Black Walnut, finish to 320 grit and oil with a non toxic all natural linseed and beeswax mix. Each sphere includes washers and M6 cap machine screw. Please note that the sphere does not have a rosette. A solid connection is made when the teeth of the bracket's rosette bite into the wood.