Rich...right explanation, wrong name for the trigger. The sequential-trip trigger is the one that forces you to compress the nose safety first, then pull the trigger, and only one nail will fire until you repeat the process (it must always happen in this SEQUENCE). A "bump-fire" trigger is one where you can hold down the trigger and fire a nail every time you compress the nose safety (or vice versa--you can still compress the nose safety then pull the trigger). The bump-fire method is for production and is considered less safe (you could be holding the trigger and bump your hand, foot, leg, whatever). My Bostitch came with the bump-fire installed, and I eventually swapped it with the sequential-trip.