Matala Air diffuser Discs are 12 inches in diameter and are designed for the pond and wastewater treatment industry to very high standards. The air pore size in the rubber membrane is designed to give a medium size bubble which will not put any significant back pressure on the system. In fact, this special air disc only adds less than 6 inches of water depth back pressure. The 3/4″ male thread makes it easy to attach to your feed line. Capable of handling air flows of 80 lpm to 200 lpm. The disc is very low maintenance and in some cases NO maintenance at all. Simply wash the disc with clean water if it ever needs cleaning.