Porta-Pak Express deodorizer sachets utilize the Walex wave2 odor control technology to deliver unsurpassed long-term odor prevention for all caravan, boat and recirculating toliet applications. Plus Porta-Pak Express provides the ease of use and convenience of a pre-packaged portion control system. The commerical strength water-soluble sachet disperses quickly into water and will not clog pipes, pumps or valves. Continued use of Porta-Pak Express will keep your toilet odor- free and hassle-free! No need for messy liquid or chalky tablets!