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.