Feature: 100% Brand new and high quality Practical and durable home using product Creates bubbles in fish tank while attached to an air pump. Used to increase the dissolved O2 level in the aquarium. It is an important instrument to successfully keep aquatic fish for respiration process. Material: Mineral, Metal Size: N-50(Internal diameter5cm, External diameter7cm) N-100(Internal diameter10cm, External diameter13cm) N-150(Internal diameter13.6cm, External diameter15.6cm) N-200(Internal diameter187cm, External diameter270cm) Package content:1pcs Air Stone/ 1pcs Air Stone+2m oxygen Pipe+1pcs valve Please let the stone soak in water for about 24 hours before use.