When it comes to keeping your RV fresh and odor-free, you need a powerful, reliable holding tank deodorizer. That's why you need the Walex Porta-Pak RV Black Holding Tank Deodorizer Drop-Ins. These little deodorizers are some of the strongest, most effective on the market, and they come in a pre-packaged, portion-controlled format that makes them easy to use without any spills. The Walex Porta-Pak RV Black Holding Tank Deodorizer Drop-Ins are ideal for breaking down waste and paper, and they're formulated to be non-staining and formaldehyde-free. They're also the #1 selling portion-controlled deodorizer in the world, so you can rest assured that you're getting a high-quality product. To use, simply drop one Walex Porta-Pak RV Black Holding Tank Deodorizer Drop-In into your holding tank and close the lid. The deodorizer will start working immediately to prevent odors and keep your RV smelling fresh. If you're looking for a powerful, easy-to-use holding tank deodorizer, the Walex Porta-Pak RV Black Holding Tank Deodorizer Drop-Ins are the perfect solution.