Green Piece® Universal Silicone Plug Caps for Cleaning, Storage, Glass Bottles - Waterproof, Reusable, Multi-Purpose Stoppers (Set of 3, Colors Vary) - Perfect for Kitchen, Bathroom, Lab & DIY Projects

I have a really strange project that required me to put a refill hole on the bottom of a spray bottle so it could be refilled while upside down. Anyway, I wasn't really sure what to use, but I found this product and gave it a shot. It works perfectly by using the two smallest plugs together it makes one very strong plug of the perfect size hole. It seals really well so I can refill the water bottle right side up as well and there's no dripping, even if it sits for a long period of time. Very happy with this product, and the fun coloring is a plus.