"The Arca Swiss D4 Geared Tripod Head Quick Set (Classic) is a symbiosis between a spherical head and a 3D tilt head. The head is very small, even compact and the levers that otherwise get in the way have been consigned to history. On a tripod, the D4 can be used like a normal spherical head.If the x and Y axes are open, one can move the camera freely. In contrast to standard spherical heads, the D4 allows one to perform the movements separately, one at a time. This can even be done with both axes open, if one of the axes is fixed this may be performed even more precisely.A rotating device, which allows camera alignment, is to be found on the base of the head. The second panorama is above the axes and allows the performance of a perfect panorama shot with an already aligned camera.The D4's innovative design puts the centre of rotation of the x and Y movements in the same place, making the pivoting radius of these movements very small, thus allowing users to maintain perspectives already found during readjustment.The head's swiveling is equipped with a self-locking shock absorption feature, allowing for near total compensation of the camera's weight.Another noticeable feature is the positioning of the spirit levels, which are located underneath the upper panorama adjustment and are arranged at a 90-degree angle.Both are sufficiently well visible as to allow photographers effective leveling, even from a low viewpoint."