Air Curtain Air Diffusers - 38cm ( 23" ) - 4 Ceramic weights - The Power Agitator - Flexible, porous air tubes with large surface area - Provide powerful aeration and water agitation - Complete with ceramic weights to hold in place - Can be formed into many shapes to produce beautiful bubble displays and air curtains - Requires very little pressure - Does not consume oxygen vital to fish - Include cleaning ring that slides along the tube to prevent clogging - Safe for fresh or salt water