It keeps your cup clean and free from lime deposits. Place the unit in the water outlet of the pump into the bowl. The water through the unit is enriched with disinfectant. Colour green or blue water and deodorizes. Each unit is supplied with two pills, a marine (blue) and pine (green) respectively. The pills also are sold separately, but the DSRU is designed to use any pill less than 30 x 30 x 40 mm. It is very easy to install, has a compact design and reduced.