Combination Wrenches
On one side of the handle, combination wrenches have a box end, and on the other, they have an open end. The box end is a closed head end that wraps around and clutches the fastener's entire head. It has more contact with the fastener than an open end and can apply more torque since the box end is less likely to fall off the fastener than an open end. The box end can only reach a fastener from the top, but the open end can access it from both the top and the side.