The present invention relates to a medical device comprising:a distal assembly including a first plurality of legs (240a) and a second plurality of legs (240b) , wherein the first plurality of legs and the second plurality of legs meet at a distal tip (230)；a first driver (260a) and a second driver (260b), wherein a proximal end of at least one leg of the first plurality of legs is coupled to the first driver, and a proximal end of at least one leg of the second plurality of legs is coupled to the second driver； anda first longitudinally extending hollow member (270a) movably positioned along the first driver；wherein movement of the first longitudinally extending hollow member (270a) relative to the first driver converges legs of the first plurality of legs, and wherein movement of the first longitudinally extending hollow member (270a) relative to the first driver does not converge legs of the second plurality of legs.
