This is a 4 pack of sponges that are about 2 inches big. I put 1 of these in the water dish to give them a safe place when in the water dish. I boiled the sponges before i added 1 to the water dish. Trad e them out every week then boiled all again to make sure there is no molds growing in the sponges. #rankboosterreview #Sponsored #sungrow https://www.amazon.com/4-Pack-Sponges-Hermit-Moisture-Hydrated/dp/B074HJ4KRQ