Pentair Aquatic Eco-Systems Sweetwater diffusers are the highest-quality ceramic-type air diffusers on the market today. They're machined from a solid block of glass-bonded silica. Because dust and dirt particles up to 30 microns in size will pass right through these diffusers, there's no need for expensive air filters. And with an air resistance of less than .25 psi, Sweetwater glassbonded diffusers are compatible with economical low-pressure blowers.They produce a uniform medium/fine bubble and are very resistant to clogging. And when cleaning does become necessary because of a buildup of calcium precipitate or bacteria, an acid bath restores them to like-new performance. W:1.5" L:12" AES:27 Air Supply Connector: 1/4" O.D. (6 mm), PE