a handle configured to receive a user input for manipulating the surgical instrument, wherein the handle includes a first handle member that rotates along a first input axis and a second handle member that rotates along a second input axis, wherein the first handle member includes a first elongated portion and the second handle member includes a second elongated portion, and the handle has an input angle defined by an angular relationship of the first elongated portion and the second elongated portion;

an end-effector configured to perform a surgical operation, wherein the end-effector includes a first jaw member and a second jaw member, each rotates along an output axis, wherein the first jaw member includes a first contact surface and the second jaw member includes a second contact surface, wherein the first contact surface and the second contact surface face each other, and the end-effector has a closed configuration, in which the first contact surface and the second contact surface are in contact with each other, or an open configuration in which the first contact surface and the second contact surface are separated from each other; and

a pulley-wire mechanism operatively connected to the handle and the end-effector, wherein the mechanism includes a first input pulley operatively connected to the first handle member, a first output pulley operatively connected to the first jaw member and operatively connected to the first input pulley via a first wire, a second input pulley operatively connected to the second jaw member, and a second output pulley operatively connected to the second jaw member and operatively connected to the second input pulley via a second wire; and

wherein when the handle has the input angle being greater than or equal to a first predetermined angle, the end-effector has the open configuration, and an angle between the first contact surface and the second contact surface changes in response to rotation of at least one of the first handle member and the second handle member, and

when the handle has the input angle being less than the first predetermined angle, the end-effector remains in the closed configuration, and a pressure between the first contact surface and the second contact surface changes in response to rotation of at least one of the first handle member and the second handle member.