Double Venturi nozzles consist of two diffusers. Due to the stream of air driven through at high velocity, there exists a negative pressure zone, which draws more air in the nozzle than that provided by the air compressor and reduces the medium velocity when blasting sand. Since the caliber of the double Venturi nozzle is larger than the single one, the size of the abrasive flow will be 35%-40% bigger, resulting in a higher clearing efficiency. I HAVE A FULL LINE OF ABRASIVE / SANDBLAST EQUIPMENT AVAILABLE. SEE MY OTHER LISTINGS