The entire toy appears to be free of pitting or other machining damage. We started with the smallest sphere, first, and frankly have stayed with that one for now. The material is smooth and easy to clean especially considering where it is intended to be inserted. We go the extra step to remove the hemisphere and clean both it and the handle independently for extra precaution. For the MSRP and the quality, this is an easy recommendation to make for beginners and advanced users alike.