When I started using the Kaboom Never Scrub toilet cleaning system, I ordered the starter kit and refills.  I was pleased to find that our toilets looked clean and a hard-water ring did not appear as it usually does.  I didn't much care for the odor of bleach when flushing, but I could live with it.

I was so pleased that I gave my friend a starter kit and refill.

When it came time to replace the original cartridge, I could not remove it.  I tried everything:  Soaking it in vinegar, soaking it in LimeAway, using a strap wrench, and asking my husband to attempt to remove it with brawn.  Nothin'....