hygger Air Stone for Aquarium: Quiet High Dissolved Oxygen Diffuser Kit for Freshwater or Saltwater Fish Tank and Hydroponic Air Pump-Disc 2 x 2 Inch Air Bubble Stone 2 PacksBrand: hygger Color: Black Features: Two packs bubble output: The air stone is made of high density corundum sand, and the high density holes form a large number of fine bubbles with low noise. Natural mineral materials will release trace elements, optimize water quality and increase fish activity, especially suitable for ornamental fish and young fish maintenance. Detailed material: The air stone for aquarium fish tank uses copper chrome plated anti