In one example, a chamber inlet assembly includes a chamber inlet, an outer coupling for a delivery line, and an inner coupling for a processing region of a processing chamber. The inner coupling and the outer coupling are on inner and outer ends, respectively, of the chamber inlet, wherein a cross-sectional area of the inner coupling is larger than a cross-sectional area of the outer coupling. The chamber inlet assembly also includes a longitudinal profile including the inner and outer ends and a first side and a second side, the first and second sides being on opposite sides of the chamber inlet, wherein a shape of the longitudinal profile comprises at least one of triangular, modified triangular, trapezoidal, modified trapezoidal, rectangular, modified rectangular, rhomboidal, and modified rhomboidal. The chamber inlet assembly also includes cassette including the chamber inlet and configured to set into a side wall of the processing chamber.