The bubble stone is made of sintered stone and plastic, and it is safe and non-toxic. it can help to create many oxygenating bubbles within your aquarium. It is reusable and durable for long time use. Features: Made from high quality sintered stone and plastic, environmentally friendly, durable and stable. Help to dissolve more oxygen, increasing the amount of oxygen in the water. Ideal for creating many oxygenating bubbles within your aquarium. Easy to use, simply connect airline and air pump to the bubble stone, and place in the aquarium Strombuliform shaped bubble stone design, unique and fashionable, perfect for decorating any fish tank. Specification: Condition: 100% Brand New Material: Plastic, Sintered Stone Color: Grey Fitment: 4mm/8mm Standard Interface Diameter: approx. 10.5cm/ 4.13in Height: approx. 5.2cm/ 2.0in Weight: approx. 330g Package List: 1* Bubble Stone Notes: 1. Please allow 0-2cm error due to the manual measurement. Thanks for your understanding. 2. Monitors are not calibrated same, item color displayed in photos may be showing slightly different from the real object. Please take the real one as standard.