This is a very nice fixture, seems well made, solid materials. There are three arms with sockets on either end and three shorter arms with no sockets, all six arms can be rotated on one axis to adjust the spread of the sockets. As a result the width and height will change by a few inches depending on where you position the arms.  
Mounting rod is multiple pieces (I believe 6", 12", 24"), so height is adjustable. 

Looks great with Edison bulbs, works on a dimmer without issues, wiring is simple and good quality.