The 360 Siphon ® RV holding tank vent cap remove odors from the source the holding tanks and exhausts them out the roof vent before they have a chance to invade the RV living space. By design, the patented 360 Siphon can only create an updraft, expelling odors and fostering an oxygen-rich environment to speed up waste breakdown. Even environmentally-friendly tank additives can take up to 48 Hours after use to fully oxygenate a standard holding tank. The 360 Siphon acts immediately after installation in any wind condition (with or without a breeze) to provide the ideal environment for proper decomposition.