Porta-Pak is the top-selling portion-control deodorizer in the world manufactured by the Walex the odor control experts. The slide-zipper bag contains ten water-soluble drop-in packets. The lavender-scented water-soluble packet controls odors breaks down waste and paper and lubricates valves and seals. Porta-Pak s premium formula works even in the heat of summer. The high-performance packet is formaldehyde-free. To use Porta-Pak drop one packet in the toilet and flush to add water. One Porta-Pak provides week-long odor control for up to a 40-gallon black tank.