RUBBER AIR CURTAIN BUBBLE WALL DIFFUSER FOR AQUARIUM FISH TANK PUMP STONE BAR Key Features Soft Black Rubber Material Flexible Provides Decoration Opportunities Adds Water Movement and Aeration to your Aquarium Variety of Lengths. Fits 4mm Air Tube. Suitable for Salt and Fresh Water Tanks *Please Note* The 30cm and 45cm Air Curtains require 1 air input and the 60cm, 75cm and 90cm require 2 air inputs. Specifications Variety of Lengths: 300 / 450 / 600 / 750 / 900mm Fits 4mm Air Tube Flexible Soft Rubber Material Colour: Black