Some of the main design parameters for double rectangular nozzles are the inside contraction angle, the length-to-width ratio of the rectangular slot, the spacing between two slots, and the angle between the two adjacent slots. The inside contraction angle and slot dimensions and spacing were varied and water application patterns and droplet diameters at the end of the spray stream were evaluated. Pattern radius decreased as slot spacing increased and increased as the length-to-width ratio increased. Sprinkler pattern and droplet diameter were insensitive to the inside contraction angle. The nozzle discharge coefficient was independent of all investigated parameters. Sprinkler rotation speed decreased with slot spacing but increased with the length-to-width ratio.