The pull-out hose puts less stress on the valve.
Blackburn's Presta-only thread-on head sits on a short pull out hose to give more options on which position you pump from. Nervous about unthreading that valve when removing the pump? Enter one of the Core's awesome features: the Presta Valve Tool. Simply unthread the tool from the back of the pump and tighten your valve prior to threading the hose on. With a larger diameter barrel, this is a perfect pump to inflate your larger volume MTB tires without fuss.