Chair is unsafe and unstable.  The base snapped shortly after purchase due to improper weight distribution and cheap metal in the base.  Any forward movement while sitting in it causes the entire chair to tip over forward and dump you onto the floor.  The shift in weight obviously is what broke the cheap base.  Read the reviews on other sites.  There are plenty of examples of this issue and many other problems.  For the price, this chair is a complete lemon!  I would give it zero stars if I could.