Abstract: Flame outlet rail for a gas burner of the atmospheric, pre-mix type. The rail includes a shell defining a plenum closed at one end and open at another end to receive an air/fuel mixture and having a length between the ends. The shell has a longitudinal orifice extending along the length of the shell. A grid made of sheet metal pierced by a series of rectangular slits is positioned over the longitudinal orifice of the shell and communicates an interior of the shell with the exterior thereof to permit the air/fuel mixture to flow therethrough so as to form a flame front upon ignition. The grid has a longitudinal axis in parallel with the longitudinal orifice and a length. The slits which extend perpendicular to the longitudinal axis, are distributed on either side of the longitudinal axis and form a sinusoid extending over the entire length of the grid, which increases a length of the flame front. The slits (2) are spaced apart by a distance, e, constant along the longitudinal axis (3) of the flame outlet grid.