Optional gauge and drain ports;Suitable for 4.5” x 10” cartridges;NPT connection ports 1”;Reversible Mounting Bracket;Pressure-relief feature includes an O-ring seal, no spring is used that can result in a water leak;Designed to the highest standard in the industry;More effective than chemicals in destroying certain waterborne contaminants without altering the taste of water;Environmentally responsible way of treating your water;ncludes blue O-ring to avoid confusion with competitors black O-rings;Accessories included-housing wrench, and LubriKit for O-ring lubrication