An end effector for use with a surgical instrument, comprising: a first jaw defining a first jaw longitudinal axis between a first jaw proximal end and a first jaw distal end thereof and comprising a plurality of first jaw stiffener features (2650, 2652) longitudinally offset from each other to define a first jaw opening therebetween; a second jaw movably coupled to said first jaw such that said first jaw and said second jaw are movable relative to each other between a fully open and a fully closed position, said second jaw comprising a plurality of second jaw stiffener features (2734, 2735) longitudinally offset from each other to define a second jaw opening therebetween; and means for selectively moving said first and second jaws between said fully open and said fully closed positions, wherein the means for selectively moving comprises an axially movable dynamic clamping assembly that is selectively movable between a starting position corresponding to said fully open position of said first and second jaws and an ending position, said axially movable dynamic clamping assembly comprising: a vertically extending body portion; at least one first jaw engagement feature configured to slidably engage said first jaw; and at least one second jaw engagement feature configured to slidably engage said second jaw; wherein either said at least one first jaw engagement feature is viewable through at least one of said first jaw openings in said first jaw or said at least one second jaw engagement feature is viewable through at least one of said second jaw openings in said second jaw as said dynamic clamping assembly is axially moved within said end effector; characterised in that when said first and second jaws are in said fully closed position, each of said first jaw stiffener features is in vertical registration with a corresponding one of said second jaw openings and each of said second jaw stiffener features is in vertical registration with a corresponding one of said first jaw openings. a first jaw defining a first jaw longitudinal axis between a first jaw proximal end and a first jaw distal end thereof and comprising a plurality of first jaw stiffener features (2650, 2652) longitudinally offset from each other to define a first jaw opening therebetween; a second jaw movably coupled to said first jaw such that said first jaw and said second jaw are movable relative to each other between a fully open and a fully closed position, said second jaw comprising a plurality of second jaw stiffener features (2734, 2735) longitudinally offset from each other to define a second jaw opening therebetween; and means for selectively moving said first and second jaws between said fully open and said fully closed positions, wherein the means for selectively moving comprises an axially movable dynamic clamping assembly that is selectively movable between a starting position corresponding to said fully open position of said first and second jaws and an ending position, said axially movable dynamic clamping assembly comprising: a vertically extending body portion; at least one first jaw engagement feature configured to slidably engage said first jaw; and at least one second jaw engagement feature configured to slidably engage said second jaw; a vertically extending body portion; at least one first jaw engagement feature configured to slidably engage said first jaw; and at least one second jaw engagement feature configured to slidably engage said second jaw; wherein either said at least one first jaw engagement feature is viewable through at least one of said first jaw openings in said first jaw or said at least one second jaw engagement feature is viewable through at least one of said second jaw openings in said second jaw as said dynamic clamping assembly is axially moved within said end effector;