Not sure - they're disposable orange ones we have here at work that come 2 in a package. Look like post #37.Hard yellow foam cylinders or soft foam bullets? I can't stand the original 3M yellow cylinders for many of the reasons you state but the soft foam bullets take many seconds to expand and I have no issues. Correct, you can not reposition them once expanded, but you shouldn't need to. Push them all the way in on the first shot.