If you can't fit a sponge inside of your favorite reusable water bottle, these Sponge Ballz Bottle Cleaning Balls are coming to your rescue! The balls are made of silicone, and are super simple to use. Simply place the balls into the water bottle with a bit of soap and warm water, and shake them around. The edges of the silicone balls will scrub clean the hard-to-reach sides of your water bottle. The balls are reusable, dishwasher safe, and come packaged in a hanging blister pack.