Lots of internets, I think you could easily find out more. Maybe just ask a speech pathologist. It works for some people permanently, some people it creates short term relief/fluency, others little effect or none. My understanding is it works best for those with a 'repetitive' stammer (ie - st..st..st..st..stammer). Not so good with 'blocks', ie- st................ammer. You dont know until you try it out, I hope it works for you. Good luck.