No more need for loose granules! With this handy holder that goes inside your water tank, you can now use SMART Anti-Scale cartridges instead of loose granules. The anti-scale cartridges ensure that your water is perfectly filtered and lengthen your systems life by preserving the boilers parts, all while improving steam quality. Clean and practical. For use with models: Laurastar S Pure Xtra, Pulse, S7a, S5, S4, and S3