Abstract: An improved low NO.sub.x burner for firing fuels such as fuel oil, fuel gas and the like having an improved register which includes primary and secondary registers. The primary and secondary registers each have an annular perforated shield covering primary and secondary air inlets. The annular perforated shields form primary and secondary air equalizers which provide a more uniform distribution of combustion air about the register as the combustion air enters the register through primary and secondary air inlets, increasing regulation of combustion air and reducing flame impingement. Annular primary and secondary dampers adjustably cover the primary and secondary air equalizers to slidably adjust the ratio of primary to secondary air entering the primary and secondary registers through the primary and secondary air inlets.