20G SWOOSH Drain Gun Cartridge. The SWOOSH® Drain Gun is designed to blow out drain lines instantly. New larger 20 gram SWOOSH CO2 cartridges deliver 800 PSI of oil free air to clear the line, with 25% more capacity. Each unit comes equipped with a tapered fitting to work on 3/8in. – 3/4in. drain openings. Flexible hose assembly maneuvers through cabinets, coils and hard to reach drains. Reduces labor costs and time on service calls.1.53 Vapor Density, Drain Gun with Tapered Fitting/Flexible Hose Assembly