This head-chemical unit dispenses a biodegradable compound to clean and lubricate your head and hoses with each flush, leaving a smooth, stain-resistant coating behind that helps control debris buildup. Tablets last about 30 days for liveaboards and much longer for weekenders. The dispenser can be installed in any position, anywhere in the 3/4'' pump inlet hose. Dispenser comes with one introductory tablet.