I don’t have a problem clenching with vulcanite. It’s my preferred stem material, so I went that route instead.The BJ Long ones fit the MM cob stems and all of the other various pipes I have. The plastic MM stems are too small and hard and make my teeth hurt. I chewed up my first cob stem, then got a replacement and started using the softies with it and then on all my pipes. They work well for me.