1、Sturdy and durable, good air dispersal, good filtering. 2、Can widely used in a variety of places, suitable for aquarium, fish tanks, etc. 3、Will keep your fish healthy and add aesthetic feeling to your aquarium, aquarium necessity. 4、Can increase oxygen content, reduce carbon dioxide and increase acidity alkalinity can produce water flow. 5、Important tool for maintaining the respiration process of fish in aquarium. Condition: 100% Brand New Item Type: Bubble Stone Material: Sandstone Color: Green Quantity: 20PCS Suitable: Aquarium, Fish Tanks Weight: Approx. 165g Single Length: Approx. 4.1cm/1.61inch Suitable Hose Inner Diameter: Approx. 3-4mm/0.12-0.16inch Using instructions: 1. Use matching hose to connect the bubble stone, the other end of the pipe to the oxygen pump 2. Please soak the product in water for 15 minutes before use 3. Use for a long time, such as dirt blocking, bubble reduction, can be taken out of cleaning and repeated use Widely used in: 1. Aerated aeration and stirring in sewage treatment plant can prevent the sediment of large particles and remove some organic matter 2. The aeration of fish pond (aquaculture farms) to nutrient-rich water in the environment and the aeration of biological culture 3. Live fish and seafood transport oxygenate. 4. Aquariums (purifiers) purify, filter and water quality ozone cleaning and oxygen 5. Other process uses requiring diffusion of air 20 x Bubble Stone