Hi John, Good informative post comparing SRSG's to static gaps! > Yes, a rotary can be used with a 15/30 NST, but it should be a sync > rotary. Non-sync rotaries tend to destroy NST's unless many > precautions are taken. Can you say what these precautions should be -- and what the probability of failure may be in spite of using these precautions? Thanks! Michael Tandy