Doing breath work was a large part of me finally not obsessing over my stutter. I think everyone is unique and it isn’t a cure all but I look forward to my almost daily 30 min of breathing then sitting with my eyes closed after. It allows me to process my day when in a relaxed state. I also loved after the first month of doing it that my lungs felt so much more expandable. I can tell a huge difference in how I interpret my stuttering if I go multiple days without my breath work. I don’t think you need to buy anything unless it speaks to you - there’s a ton of free breathing exercises on YouTube. But I do think sitting or laying calmly with your eyes closed for at least 10 minutes after is the true benefit.