These SpinDisk® reagent cartridges are for use with the WaterLink® Spin Touch® photometer. The innovative Mobile Commercial WaterLink® Spin Touch® photometer does all your pool and spa water testing for you. Each sealed SpinDisk® reagent cartridge contains the precise amount of reagent needed to run a complete series of tests. Just fill one unique SpinDisk® reagent cartridge with less than 3 mL of water and all your vital tests are done automatically in just 60 seconds!