The New Fluidmaster 8102P8 Flush n Sparkle Automatic Toilet Bowl Cleaning System Blue Refill Cartridges 2-Pack, Blue are designed to be a fast and effective hands-free cleaning solution for most any toilet with every flush. Here the Flush n Sparkle Blue Tank Refill Cartridges are made to quickly replace old cartridges and fit both the Blue, or Bleach Systems. Installation takes only a minute, for continued hassle-free cleaning. The Flush n Sparkle Blue Tank Cleaning System puts a powerful surfactant-based cleaning solution directly into the overflow tube of the flush valve to help maintain your septic tank. No chemicals ever touch the flapper, fill valve, or other tank parts, preventing the damage drop-in tablets normally inflict, leading to deterioration and part malfunction. The Flush n Sparkle Cleaning System Refills offer a powerful toilet cleaning solution in a 2-Pack for up to 6 months of cleaning.