Scrubbing Bubbles Drop-Ins are just the remedy for yucky toilet stains. Just drop a tablet into your tank to help keep your toilet bowl stain-free up to 4 weeks. With every flush your toilet enjoys glorious relief from stains caused by hard water minerals and limescale. That s continuous odor protection for a continuous clean. Quick and hassle free! Stain and smell protection that drops right in. That s cleaning reinvented.